Power Automate Expression Syntax: The Complete Cheat Sheet (2026)

Power Automate expression syntax is a function-call language — every expression looks like functionName(argument1, argument2), never an inline operator like + or -. It runs on Workflow Definition Language (WDL), the same engine behind Azure Logic Apps (Microsoft Learn, 2026). You drop it into a flow's action inputs to transform, compare, or compute values while the flow runs. This Power Automate expressions reference covers the syntax rules first, then every function with a worked example. The parser is strict and unforgiving: single quotes only, no infix math operators, two distinct forms that aren't interchangeable. Get any one of those three rules wrong and the flow won't even save.

Need to pull just the file extension off an uploaded document? Build a subject line from three different fields? Fall back to a default when SharePoint hands you a null? That's what expressions are for. You write them in the expression editor tab of any action input field: click the field, select "Expression", type your function, click OK. The result replaces the field value at run time.

Two forms exist, and mixing them up is the single most common syntax mistake. Inline — @{functionName(args)} — embeds the result inside a string, so Hello @{triggerOutputs()?['body/Name']} produces Hello Rizwan. Pure expression — just functionName(args) with no @{} wrapper — returns the raw value and is what you type into the expression editor tab. Wrap a pure expression in @{} there and you won't get a warning — you'll get a string that starts with a literal @.

Key Takeaways

- Power Automate expression syntax is a strict, WDL-based function-call language — concat(), if(), coalesce(), and more — shared with Azure Logic Apps (Microsoft Learn, 2026).

- Use @{...} only for inline string interpolation; use bare functionName() in the expression editor tab. Mixing the two forms up is the #1 syntax mistake.

- The ? operator makes any property access null-safe: body('Get_item')?['value'] never throws on a missing field.

- coalesce() is the fastest fix for null values from SharePoint, Dataverse, or HTTP responses.

- All 90+ functions in this cheat sheet are copy-paste ready with live examples, including the workflow-reference functions (variables(), parameters(), triggerBody()) that most cheat sheets skip.

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Power Automate Expression Syntax Basics

Power Automate expressions follow a strict parser. Get these rules wrong and you'll see InvalidTemplate before the flow even runs.

Syntax rules at a glance

Five rules cover almost every InvalidTemplate error you'll hit. Bookmark this table before you touch the expression editor:

Rule	Right	Wrong
Two forms aren't interchangeable	concat('a','b') in the Expression tab	@{concat('a','b')} in the Expression tab
Strings use single quotes only	equals(toLower(x), 'done')	equals(toLower(x), "done")
No infix math operators	add(sub(10,2), 1)	10 - 2 + 1
Null-safe property access	body('Get_item')?['value']	body('Get_item')['value']
Escape a literal quote by doubling it	'O''Brien'	'O\'Brien'

Treat this table as the TL;DR — check it first when a flow won't save. The "Two forms," "Quote rules," and "Null safety" sections below walk through the first, second, and fourth rows with real SharePoint/Graph field references instead of placeholder x and 'a'/'b' values. The rest of the cheat sheet is the full function reference.

Power Automate expression syntax vs. Excel and Power Fx

If you've written Excel formulas or Power Apps' Power Fx, the biggest adjustment isn't the function names — it's that WDL has no infix operators at all. =A1+B1 in Excel and TextInput1.Text & " rows" in Power Fx both use inline symbols; Power Automate has neither. Everything, including basic addition, goes through a function call: add(10, 5) not 10 + 5. String concatenation is concat('a', 'b'), not 'a' & 'b' or 'a' + 'b'.

The second gap is quoting. Power Fx and most JSON tooling accept double quotes for strings; WDL expressions only accept single quotes. Paste a Power Fx formula straight into the expression editor and you'll get InvalidTemplate on the double quotes before anything else even runs. Retype the string literals with single quotes and the same logical formula usually works once you swap the operators for function calls.

The two forms

# Pure expression (use in the Expression tab):
concat('Hello', ' ', triggerOutputs()?['body/Name'])

# Inline interpolation (embed inside a text field):
Hello @{triggerOutputs()?['body/Name']}, your order is @{outputs('Get_order')?['body/Status']}

Never wrap a pure expression in @{...} in the expression editor — the parser will double-evaluate it and produce a string that starts with a literal @.

Quote rules

Single quotes delimit string literals. Double quotes are not valid inside expressions and will break the parser:

# Correct
replace(triggerOutputs()?['body/Title'], 'Draft', 'Final')

# Broken — double quotes cause InvalidTemplate
replace(triggerOutputs()?["body/Title"], "Draft", "Final")

To include a literal single quote in a string, escape it by doubling: 'O''Brien'.

Null safety with ?

The ? operator on a property access returns null instead of throwing when the property doesn't exist. Use it on every dynamic content reference:

# Throws if 'Manager' is null in SharePoint People column
triggerOutputs()?['body/Manager/Email']

# Safe — returns null instead of crashing
triggerOutputs()?['body/Manager']?['Email']

Chain as many ? as you need. Combine with coalesce() to substitute a default when null comes through.

Operator precedence

Power Automate expressions don't support infix math operators (+, -, *, /). Use functions: add(), sub(), mul(), div(), mod(). Parentheses control evaluation order inside function arguments exactly as you'd expect.

How to test any expression

Drop a Compose action into your flow, paste the expression in its input, and run the flow. The Compose output shows exactly what the expression returns — invaluable before wiring a complex expression into a Send Email or Condition action.

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Power Automate Expressions Reference: Function Index

Every function covered below, alphabetically. Click a category header to jump to the full table with syntax and examples.

Looking for a searchable, filterable list you can copy from rather than a guide to read? Use the Power Automate expressions reference tool — same functions, with search, category filters and one-click copy.

Function	Category	Returns
action	Workflow	Metadata for the currently running action
add	Math	Sum of two numbers
addDays	Date/Time	Timestamp ± N days
addHours	Date/Time	Timestamp ± N hours
addMinutes	Date/Time	Timestamp ± N minutes
addProperty	Object	Object with a new property added (errors if it already exists)
addSeconds	Date/Time	Timestamp ± N seconds
addToTime	Date/Time	Timestamp plus N units (Second…Year)
and	Logic	true if all conditions true
array	Conversion	Value wrapped in a single-element array
base64	Conversion	Base64-encoded string
base64ToString	Conversion	Decoded UTF-8 string
body	Workflow	The body of a named action's output
bool	Conversion	Boolean true/false
chunk	Array	Array split into sub-arrays
coalesce	Logic	First non-null value
concat	String	Joined strings
contains	String / Array	true if item found
convertTimeZone	Date/Time	Timestamp in target time zone
createArray	Array	New array
dateDifference	Date/Time	Difference as duration
dayOfMonth	Date/Time	Day number (1–31)
dayOfWeek	Date/Time	Day number (0=Sunday)
dayOfYear	Date/Time	Day number within the year (1–366)
decimal	Conversion	Decimal-precision number
decodeBase64	Conversion	Decoded string
decodeUriComponent	Conversion	URL-decoded string
div	Math	Quotient (integer)
empty	Logic	true if null/empty
endsWith	String	true if ends with
equals	Logic	true if values equal
first	Array	First element
float	Conversion	Floating-point number
formatDateTime	Date/Time	Formatted date string
formatNumber	String	Formatted number string
getFutureTime	Date/Time	Timestamp N units from now
getPastTime	Date/Time	Timestamp N units ago
greater	Logic	true if value1 > value2
greaterOrEquals	Logic	true if value1 >= value2
guid	Utility	New GUID string
if	Logic	Conditional value
indexOf	String	Position of substring
int	Conversion	Integer
intersection	Array	Common items
isFloat	Logic	true if a string parses as a floating-point number
isInt	Logic	true if a string parses as an integer
item	Workflow	Current item inside the enclosing Apply to each
items	Workflow	Current item of a named Apply to each loop
join	Array	Array joined to string
json	Conversion	Parsed JSON object
last	Array	Last element
lastIndexOf	String	Position of the last occurrence of a substring
length	String / Array	Count
less	Logic	true if value1 < value2
lessOrEquals	Logic	true if value1 <= value2
max	Math	Highest of a set of numbers or an array
min	Math	Lowest of a set of numbers or an array
mod	Math	Remainder
mul	Math	Product
not	Logic	Negated boolean
nthIndexOf	String	Nth occurrence position
or	Logic	true if any condition true
outputs	Workflow	Full output (status, headers, body) of a named action
parameters	Workflow	Value of a defined flow parameter
parseDateTime	Date/Time	ISO timestamp parsed from a locale-formatted string
rand	Math	Random integer in a range
range	Array	Array of sequential integers
removeProperty	Object	Object with a property removed
replace	String	String with substitutions
result	Workflow	Results of the first-level actions inside a Scope, For each or Until
reverse	Array	Reversed array
setProperty	Object	Object with a property set (added if missing)
skip	Array	Array minus first N
slice	String	Substring by start and end index (negative indexes allowed)
sort	Array	Sorted array
split	String	Array from split
startOfDay	Date/Time	Timestamp at 00:00:00 of its day
startOfHour	Date/Time	Timestamp at minute zero of its hour
startOfMonth	Date/Time	Timestamp at 00:00:00 on the 1st of its month
startsWith	String	true if starts with
string	Conversion	String representation
sub	Math	Difference
substring	String	Substring by index
subtractFromTime	Date/Time	Timestamp minus N units (Second…Year)
take	Array	First N elements
ticks	Date/Time	Tick count (100-ns units)
toLower	String	Lowercase string
toUpper	String	Uppercase string
triggerBody	Workflow	The trigger's output body
triggerOutputs	Workflow	Full output of the trigger (?['body/Field'] to reach a field)
trim	String	Whitespace-trimmed string
union	Array	Merged array (deduped)
uriComponent	Conversion	URL-encoded string
uriHost	Conversion	Host name of a URL
uriPath	Conversion	Path of a URL
utcNow	Date/Time	Current UTC timestamp
variables	Workflow	Value of a flow variable
workflow	Workflow	Metadata about the running flow
xml	Conversion	XML object
xpath	Conversion	Nodes or values matching an XPath expression

All functions are documented at Microsoft Learn's Workflow Definition Language Functions Reference (linked at the top of this post and again at the end).

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String Functions

These 14 string functions cover concatenation, search, replacement, padding, and formatting. These are the functions you'll use in nearly every flow that handles user data, file names, or email content — all documented in the Microsoft Learn WDL reference above.

Function	Syntax	Example	Output
concat	concat(text1, text2, ...)	concat('Hello', ' ', 'World')	Hello World
substring	substring(text, startIndex, length)	substring('PowerAutomate', 5, 8)	Automate
replace	replace(text, oldText, newText)	replace('Hello World', 'World', 'Flow')	Hello Flow
split	split(text, delimiter)	split('a;b;c', ';')	["a","b","c"]
toLower	toLower(text)	toLower('HELLO')	hello
toUpper	toUpper(text)	toUpper('hello')	HELLO
trim	trim(text)	trim(' hello ')	hello
indexOf	indexOf(text, searchText)	indexOf('Hello World', 'World')	6
nthIndexOf	nthIndexOf(text, searchText, n)	nthIndexOf('a.b.c.d', '.', 2)	3
length	length(text)	length('Power')	5
startsWith	startsWith(text, searchText)	startsWith('PowerAutomate', 'Power')	true
endsWith	endsWith(text, searchText)	endsWith('report.pdf', '.pdf')	true
contains	contains(text, searchText)	contains('Hello World', 'World')	true
formatNumber	formatNumber(number, format)	formatNumber(1234.5, 'C2')	$1,234.50

String tips

Use concat() instead of the @{...} inline syntax when combining more than two dynamic values — it's easier to debug. When checking user input, always wrap in toLower() or toUpper() first so comparisons are case-insensitive. Use nthIndexOf() to locate the second or third occurrence of a delimiter (e.g., finding the second dot in a version string like 1.20.3).

Power Automate cloud flows don't have a native padLeft() expression — use formatNumber() instead for zero-padded integers: formatNumber(triggerOutputs()?['body/ID'], '000000') turns 42 into 000042. For arbitrary string padding, the workaround is substring(concat('000000', string(triggerOutputs()?['body/ID'])), sub(length(concat('000000', string(triggerOutputs()?['body/ID']))), 6)).

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Date and Time Functions

Power Automate stores every timestamp internally as UTC. These 13 functions handle formatting, arithmetic, and time-zone conversion — the three tasks you'll need for every flow that touches dates in emails, SharePoint columns, or approval deadlines. The formatDateTime() format strings follow the .NET DateTimeFormat conventions (Microsoft Learn, 2026).

Function	Syntax	Example	Output
utcNow	utcNow(format?)	utcNow('yyyy-MM-dd')	2026-07-10
addDays	addDays(timestamp, days, format?)	addDays(utcNow(), 7, 'yyyy-MM-dd')	7 days from now
addHours	addHours(timestamp, hours, format?)	addHours(utcNow(), -3)	3 hours ago
addMinutes	addMinutes(timestamp, minutes)	addMinutes(utcNow(), 30)	30 min from now
addSeconds	addSeconds(timestamp, seconds)	addSeconds(utcNow(), 90)	90 seconds from now
formatDateTime	formatDateTime(timestamp, format)	formatDateTime(utcNow(), 'MM/dd/yyyy')	07/10/2026
convertTimeZone	convertTimeZone(timestamp, source, dest, format?)	convertTimeZone(utcNow(), 'UTC', 'Eastern Standard Time', 'hh:mm tt')	08:30 AM
getPastTime	getPastTime(interval, timeUnit, format?)	getPastTime(7, 'Day', 'yyyy-MM-dd')	7 days ago
getFutureTime	getFutureTime(interval, timeUnit, format?)	getFutureTime(1, 'Month', 'yyyy-MM-dd')	1 month from now
dayOfWeek	dayOfWeek(timestamp)	dayOfWeek('2026-07-10')	5 (Friday)
dayOfMonth	dayOfMonth(timestamp)	dayOfMonth('2026-07-10')	10
ticks	ticks(timestamp)	ticks('2026-01-01')	Tick count
dateDifference	dateDifference(startDate, endDate)	dateDifference('2026-01-01', '2026-07-10')	190.00:00:00

Date tips

formatDateTime() uses .NET custom date format strings. Common patterns: yyyy-MM-dd for ISO, MM/dd/yyyy for US, dd/MM/yyyy for EU, dddd, MMMM d, yyyy for display. Always convert to the user's time zone with convertTimeZone() before including dates in emails — Power Automate stores every timestamp as UTC internally.

getPastTime and getFutureTime are cleaner than addDays(utcNow(), -7) when you want a fixed offset from now. Valid timeUnit values: Second, Minute, Hour, Day, Week, Month, Year.

Use ticks() to compare two dates numerically — subtract them, then divide by 864000000000 to get days:

div(sub(ticks(outputs('DueDate')), ticks(utcNow())), 864000000000)

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Collection and Array Functions

Power Automate has 14 collection and array functions. They work on arrays returned by "List rows", "Get items", and HTTP responses — anywhere a multi-value result comes back and needs filtering, slicing, or merging before the next action. The PnP community maintains real-world examples of these patterns in SharePoint flows at PnP Samples if you need more context beyond this reference.

Function	Syntax	Example	Output
first	first(collection)	first(createArray('a','b','c'))	a
last	last(collection)	last(createArray('a','b','c'))	c
length	length(collection)	length(createArray('a','b','c'))	3
contains	contains(collection, value)	contains(createArray('a','b'), 'b')	true
join	join(collection, delimiter)	join(createArray('a','b','c'), '; ')	a; b; c
split	split(text, delimiter)	split('a,b,c', ',')	["a","b","c"]
union	union(collection1, collection2)	union(createArray(1,2), createArray(2,3))	[1,2,3]
intersection	intersection(col1, col2)	intersection(createArray(1,2,3), createArray(2,3,4))	[2,3]
skip	skip(collection, count)	skip(createArray('a','b','c'), 1)	["b","c"]
take	take(collection, count)	take(createArray('a','b','c'), 2)	["a","b"]
createArray	createArray(item1, item2, ...)	createArray(1, 2, 3)	[1,2,3]
reverse	reverse(collection)	reverse(createArray(1,2,3))	[3,2,1]
sort	sort(collection, sortBy?)	sort(createArray(3,1,2))	[1,2,3]
chunk	chunk(collection, size)	chunk(createArray(1,2,3,4,5), 2)	[[1,2],[3,4],[5]]

Array tips

Use empty() to check if an array has items before looping. Combine skip() and take() for pagination. union() also merges two objects (not just arrays), which is useful for building dynamic JSON payloads.

chunk() is useful when you need to process a large SharePoint list in batches — split the ID array with chunk(), then loop over each sub-array. sort() works on arrays of strings or numbers; for complex objects, sort inside a Select + Apply to Each combination. reverse() is handy when you want the most recent item from a sorted list without reversing the sort order in a query.

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Logical Functions

Function	Syntax	Example	Output
if	if(expression, valueIfTrue, valueIfFalse)	if(equals(1,1), 'yes', 'no')	yes
equals	equals(value1, value2)	equals(toLower('Hello'), 'hello')	true
and	and(expr1, expr2)	and(greater(5,3), less(5,10))	true
or	or(expr1, expr2)	or(equals(1,2), equals(1,1))	true
not	not(expression)	not(equals(1,2))	true
greater	greater(value1, value2)	greater(10, 5)	true
greaterOrEquals	greaterOrEquals(value1, value2)	greaterOrEquals(5, 5)	true
less	less(value1, value2)	less(3, 5)	true
lessOrEquals	lessOrEquals(value1, value2)	lessOrEquals(5, 5)	true
empty	empty(value)	empty('')	true
coalesce	coalesce(value1, value2, ...)	coalesce(null, null, 'default')	default

Logic tips

Don't nest if() more than two levels deep — it becomes unreadable and hard to debug. Use a Condition action instead for branching. coalesce() is the go-to fix for null values from SharePoint People columns, Dataverse lookups, and HTTP responses — it returns the first non-null value. You can use it to provide fallbacks for optional fields without a separate null check:

coalesce(triggerOutputs()?['body/Manager/Email'], triggerOutputs()?['body/Owner/Email'], 'admin@contoso.com')

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Math Functions

Power Automate has no infix operators — there is no +, -, *, or / syntax. Every arithmetic operation requires an explicit function call. This surprises developers coming from Excel formulas or Power Fx, but the WDL parser simply doesn't support operator notation (Microsoft Learn, 2026).

Function	Syntax	Example	Output
add	add(num1, num2)	add(10, 5)	15
sub	sub(num1, num2)	sub(10, 5)	5
mul	mul(num1, num2)	mul(4, 3)	12
div	div(num1, num2)	div(10, 3)	3 (integer)
mod	mod(num1, num2)	mod(10, 3)	1

Math tips

div() performs integer division — div(10, 3) returns 3, not 3.333. To get a float result, convert one operand first: div(float(10), 3). Chain functions for compound calculations: add(mul(3, 4), mod(10, 3)) gives 13. For percentage calculations, use mul(div(float(part), float(total)), 100) — the float() conversions are required or the intermediate div() will truncate.

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Conversion Functions

Type mismatches are the most common cause of InvalidTemplate and ExpressionEvaluationFailed errors in production flows. These 13 functions handle every type conversion you'll need — between strings, numbers, booleans, JSON, XML, and encoded formats. When in doubt, call string() before passing a value to a string function or int() before arithmetic.

Function	Syntax	Example	Output
array	array(value)	array('abc')	["abc"]
decimal	decimal(value)	string(decimal('1.2345678912312131'))	"1.2345678912312131"
int	int(value)	int('42')	42
float	float(value)	float('3.14')	3.14
string	string(value)	string(42)	"42"
bool	bool(value)	bool(1)	true
json	json(value)	json('{"name":"test"}')	JSON object
xml	xml(value)	xml('<root><item>1</item></root>')	XML object
base64	base64(value)	base64('Hello')	SGVsbG8=
base64ToString	base64ToString(value)	base64ToString('SGVsbG8=')	Hello
decodeBase64	decodeBase64(value)	decodeBase64('SGVsbG8=')	Hello
uriComponent	uriComponent(value)	uriComponent('hello world')	hello%20world
decodeUriComponent	decodeUriComponent(value)	decodeUriComponent('hello%20world')	hello world

Conversion tips

Use json() when an HTTP response body comes back as a string instead of a parsed object — this happens with some older REST APIs and SharePoint REST endpoints that return Content-Type: text/plain. Use xml() for SharePoint SOAP service responses. base64() and base64ToString() are commonly needed when working with attachment content in connectors like Outlook or OneDrive. uriComponent() is essential when you're building query string parameters dynamically — without it, spaces and special characters break the URL silently.

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Workflow and Reference Functions

Most cheat sheets stop at string, date, array, and math functions and skip the ones that read the flow's own state — variables, parameters, trigger data, run metadata. These 8 are what you reach for once a flow gets past "hello world" (Microsoft Learn, 2026).

Function	Syntax	Example	Output
variables	variables(name)	variables('RetryCount')	Current value of the flow variable
parameters	parameters(name)	parameters('SiteUrl')	Value of a defined flow parameter
triggerBody	triggerBody()	triggerBody()?['Title']	The trigger's output body — shorthand for triggerOutputs()?['body']
action	action()	action()?['startTime']	Metadata for the currently running action
workflow	workflow()	workflow()?['run']?['name']	Metadata about the flow itself — name, run ID, tags
guid	guid()	guid()	A new GUID, e.g. 3f2504e0-4f89-11d3-9a0c-0305e82c3301
rand	rand(min, max)	rand(1, 100)	Random integer between min (inclusive) and max (exclusive)
range	range(start, count)	range(1, 5)	[1,2,3,4,5]

Workflow function tips

variables() only works after an Initialize variable action has run earlier in the flow — reference it before that action runs and you'll get a null reference error, not a helpful message. triggerBody() is the one to reach for instead of the longer triggerOutputs()?['body'] when you just need the trigger's payload with no headers or status code. guid() is handy for generating idempotency keys before an HTTP POST, so retries don't create duplicate records downstream. range() combined with an Apply to each loop is the standard way to run an action a fixed number of times when there's no collection to iterate over.

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Dates, Objects, Loops and URIs: The Functions Most Cheat Sheets Skip

The tables above cover the functions you use every day. These 25 are the ones you go looking for when a flow needs something specific. Think of a "first of the month" report date, a JSON payload with one field changed, the current item of a named loop, or the host name out of a URL. Every one is in the Microsoft Learn WDL functions reference (2026); the examples below are the documented ones, with 2026 dates.

More date and time functions

Function	Syntax	Example	Output
startOfDay	startOfDay(timestamp, format?)	startOfDay('2026-03-15T13:30:30Z')	2026-03-15T00:00:00.0000000Z
startOfHour	startOfHour(timestamp, format?)	startOfHour('2026-03-15T13:30:30Z')	2026-03-15T13:00:00.0000000Z
startOfMonth	startOfMonth(timestamp, format?)	startOfMonth('2026-03-15T13:30:30Z', 'yyyy-MM-dd')	2026-03-01
addToTime	addToTime(timestamp, interval, timeUnit, format?)	addToTime('2026-01-01T00:00:00Z', 1, 'Day')	2026-01-02T00:00:00.0000000Z
subtractFromTime	subtractFromTime(timestamp, interval, timeUnit, format?)	subtractFromTime('2026-01-02T00:00:00Z', 1, 'Day')	2026-01-01T00:00:00.0000000Z
dayOfYear	dayOfYear(timestamp)	dayOfYear('2026-03-15T13:27:36Z')	74
parseDateTime	parseDateTime(text, locale?, format?)	parseDateTime('20/10/2026', 'fr-fr')	2026-10-20T00:00:00.0000000

addToTime() and subtractFromTime() take the same timeUnit values as getFutureTime() — Second, Minute, Hour, Day, Week, Month, Year — but start from a timestamp you supply instead of from now. That makes them the right call for "due date = created date + 2 weeks":

addToTime(triggerOutputs()?['body/Created'], 2, 'Week', 'yyyy-MM-dd')

startOfMonth() is the clean way to build a month-to-date filter for a "Get items" query. parseDateTime() is the only safe way to read a dd/MM/yyyy string typed into a form: formatDateTime() will read 03/04/2026 as March 4 unless you parse it with the right locale first.

More string, math and type-check functions

Function	Syntax	Example	Output
lastIndexOf	lastIndexOf(text, searchText)	lastIndexOf('hello world hello world', 'world')	18
slice	slice(text, startIndex, endIndex?)	slice('Hello World', 2)	llo World
min	min(num1, num2, ...) or min(array)	min(createArray(1, 2, 3))	1
max	max(num1, num2, ...) or max(array)	max(1, 2, 3)	3
isInt	isInt(text)	isInt('10')	true
isFloat	isFloat(text, locale?)	isFloat('10.000,00', 'de-DE')	true

slice() accepts negative indexes, so slice(variables('FileName'), -4) returns the last four characters — a shorter way to get a .pdf extension than the substring() + length() arithmetic. isInt() and isFloat() are the guard to put in a Condition before calling int() or float() on form input; without them a stray space turns into an ExpressionEvaluationFailed at runtime. min() and max() take an array directly, so they pair with a Select action that pulls one numeric column out of "Get items".

Object functions

Function	Syntax	Example	Output
setProperty	setProperty(object, property, value)	setProperty(json('{"a":1}'), 'a', 2)	{"a":2}
addProperty	addProperty(object, property, value)	addProperty(json('{"a":1}'), 'b', 2)	{"a":1,"b":2}
removeProperty	removeProperty(object, property)	removeProperty(json('{"a":1,"b":2}'), 'b')	{"a":1}

addProperty() throws at runtime if the property already exists; setProperty() adds it when missing and overwrites it when present, so it is the safer default. To change a nested field, nest the calls — setProperty(obj, 'parent', setProperty(obj['parent'], 'child', value)) — because a bare inner call returns only the child object. These three are how you patch an HTTP request body without a Parse JSON + Compose round trip.

Loop and action functions

Function	Syntax	Example	Returns
item	item()	item()?['Title']	The current item of the enclosing Apply to each
items	items(loopName)	items('Apply_to_each')?['Title']	The current item of the named loop — use in nested loops
outputs	outputs(actionName)	outputs('Get_user')?['body']	The action's full output: status code, headers and body
body	body(actionName)	body('Get_user')?['displayName']	Just the body — shorthand for outputs('...')?['body']
triggerOutputs	triggerOutputs()	triggerOutputs()?['body/Title']	The trigger's full output; triggerBody() is the body-only shorthand
result	result(scopeName)	result('Scope_Try')	An array with status, inputs and outputs of each first-level action in the scope

Inside two nested Apply to each loops, item() always means the innermost loop; reach the outer item with items('Outer_loop_name'). result() is the basis of the try/catch pattern: put the risky actions in a Scope, set a second Scope to run only on failure, and read result('Scope_Try') there to log which action failed and why.

URI and XML functions

Function	Syntax	Example	Output
uriHost	uriHost(uri)	uriHost('https://www.localhost.com:8080')	www.localhost.com
uriPath	uriPath(uri)	uriPath('https://www.contoso.com/catalog/shownew.htm?date=today')	/catalog/shownew.htm
xpath	xpath(xml, xpathExpression)	xpath(xml(body('HTTP')), '/order/items/item/text()')	Array of matching nodes or values

uriHost() and uriPath() save the split() gymnastics when a SharePoint hyperlink column or an HTTP trigger hands you a full URL. xpath() runs on the .NET XPath library, so stick to XPath 1.0 syntax; wrap the string in xml() first or the function fails with a type error.

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Common Production Patterns

These are the expressions you'll copy-paste most often in real flows — tested patterns for the date formatting, null handling, HTTP parsing, and subject-line building scenarios that come up in almost every approval or notification flow.

Format a date for emails

When SharePoint returns an ISO timestamp and you need a clean display date:

formatDateTime(triggerOutputs()?['body/Created'], 'MMMM d, yyyy')

Output: July 10, 2026. For the US short format: formatDateTime(..., 'M/d/yyyy').

Get file extension from a filename

last(split(triggerOutputs()?['body/{FilenameWithExtension}'], '.'))

Splits report-final.pdf on . and returns pdf. Works for any delimiter-based extraction.

Null-safe field access with fallback

coalesce(triggerOutputs()?['body/Manager/Email'], 'no-manager@contoso.com')

For numeric fields that might be null:

coalesce(triggerOutputs()?['body/Amount'], 0)

Build a dynamic email subject

concat('[', triggerOutputs()?['body/Department'], '] ', triggerOutputs()?['body/RequestType'], ' - ', triggerOutputs()?['body/Title'])

Output: [Finance] Purchase Order - Office Supplies Q2

For end-to-end approval flows using this pattern, see the Power Automate document approval workflow guide.

Calculate days between two dates

div(sub(ticks(outputs('EndDate')), ticks(outputs('StartDate'))), 864000000000)

Each tick is 100 nanoseconds; 864000000000 ticks = 1 day. For business-days counting (excluding weekends), store holidays in a SharePoint list and subtract them in a loop.

Parse a JSON response from an HTTP action

json(body('HTTP_Request'))?['results']

Safe nested access:

coalesce(json(body('HTTP_Request'))?['data']?['value'], 'Not found')

For calling external APIs with OAuth from Power Automate flows, see the custom connectors guide.

Build styled HTML for email output

Expressions can build HTML strings inline:

concat('<b>', triggerOutputs()?['body/Title'], '</b><br/>', formatDateTime(triggerOutputs()?['body/DueDate'], 'MMMM d, yyyy'))

For applying CSS to HTML tables generated by flows, see Power Automate HTML table styling with CSS.

Practical note: the expression editor in Power Automate (and the underlying WDL engine) shares its function library with Azure Logic Apps. If you find a function in the Logic Apps reference that isn't in the Power Automate UI docs, try it anyway — it usually works. Microsoft keeps the two runtimes in sync but the UI docs sometimes lag by months.

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Quick Reference: Expression Editor Shortcuts

A few things that trip up new users every time:

• Accessing dynamic content in expressions: Use triggerOutputs(), outputs('ActionName'), or body('ActionName') to reference values — never paste raw dynamic content tokens into the expression editor.

• Optional chaining: The ? operator (e.g., body('Get_item')?['value']) prevents errors when a property doesn't exist.

• Nested quotes: Use single quotes inside expressions. Double quotes break the parser.

• Testing expressions: Use a Compose action — the output shows exactly what the expression returns before you wire it into something consequential.

• Type mismatches: If equals() returns false when you expect true, one side is probably a string and the other is an integer. Use int(), float(), or string() to normalize.

To look a function up quickly rather than read it in context, use the Power Automate expressions reference tool. It lists every function with its syntax and a worked example, filterable by category and copyable in one click. Nothing evaluates expressions outside Power Automate itself — a Compose action remains the only way to see what one actually returns. The same expression patterns apply in Power Apps canvas formulas, too — see the Power Apps canvas app + SharePoint guide for side-by-side examples.

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Common Expression Syntax Errors and Fixes

These are the errors Power Automate throws most often when expression syntax is wrong — with the exact message and what to change.

InvalidTemplate on save

Full error:

InvalidTemplate. Unable to process template language expressions in action '...' inputs at line '...' and column '...': '...'. Please see https://aka.ms/logicexpressions for usage details.

Causes and fixes:

Root cause	Fix
Double quotes inside expression	Replace "value" with 'value'
Unmatched parentheses	Count opening vs closing parens — add a missing )
@{...} wrapper inside the expression editor	Remove the @{ and } — they're for inline interpolation only
Referencing an action name with spaces	Wrap in quotes: outputs('My Action') not outputs(My Action)

ExpressionEvaluationFailed at runtime

Full error:

The execution of template language expression '...' failed: 'The template language function '...' expects its parameter to be a string...

Type mismatch. SharePoint list columns return different types depending on the field type. A Number column returns an integer; pass it to a string function and you'll hit this. Fix with string(triggerOutputs()?['body/Count']).

NullValueInArgumentError at runtime

The execution of template language expression 'first(triggerOutputs()?['body/value'])' failed: '...array was null or empty'.

The array was empty. Wrap with an empty() guard:

if(empty(triggerOutputs()?['body/value']), 'No items', first(triggerOutputs()?['body/value'])?['Title'])

ActionInputsNotFound for dynamic content

This isn't an expression syntax error — it means the action you're referencing in outputs('ActionName') doesn't exist or has been renamed. Check the internal name of the action (visible in the "..." menu of the action → rename) and update the expression.

div() returns 0 unexpectedly

div() is integer division. div(5, 10) returns 0 not 0.5. Convert to float first:

div(float(5), float(10))

From real flows: the most common syntax error I see in shared flow templates is action names with special characters — Get item becomes Get_item internally but Get_item_2 if it was renamed. Always use the Dynamic Content pane to grab the exact internal name rather than guessing the string to put inside outputs().

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FAQ

What are Power Automate expressions used for?

They handle anything a static field can't:

• Pulling a file extension off an uploaded document

• Building a subject line from three different fields

• Converting a UTC timestamp to the reader's time zone

• Falling back to a default when a SharePoint column comes back empty

Anywhere a flow needs to transform, compare, or compute a value on the fly instead of using a fixed input, you reach for an expression. That means concat(), if(), formatDateTime(), or one of the other 90-odd functions in this cheat sheet. Not sure whether you need one? Ask: "does this value change based on what the trigger sends in?" If yes, it's an expression, not a hardcoded string.

What is Power Automate expression syntax?

Power Automate expression syntax is the function-call grammar of the Workflow Definition Language (WDL), the same engine Azure Logic Apps runs on (Microsoft Learn, 2026). Every expression takes the form functionName(argument1, argument2, ...) — there's no infix math, no double-quoted strings, and no bare property access without the null-safe ? operator. You type it into the Expression tab of any action field, or wrap it in @{...} to interpolate it inside a text field.

What is the difference between concat() and inline @{...} syntax?

concat() is a function you call in the expression editor. @{...} is an interpolation syntax you use directly in text fields (not the expression tab) to embed an expression result mid-string. They produce the same output but live in different places. Use concat() when you need to combine more than two values — it's easier to debug. Use @{...} for simple inline substitutions in text fields like email subjects.

Can you nest expressions inside other expressions?

Yes — this is how most real expressions work. if(empty(triggerOutputs()?['body/Email']), 'N/A', toLower(triggerOutputs()?['body/Email'])) is a nested expression combining if, empty, and toLower. Watch your parentheses — one missing ) causes InvalidTemplate with a line/column pointer that's often off by one.

How do you handle time zones in Power Automate?

All timestamps in Power Automate are stored as UTC internally. Use convertTimeZone(utcNow(), 'UTC', 'Eastern Standard Time', 'hh:mm tt') before displaying dates to users. The full list of supported time zone names is in the Microsoft Learn reference linked at the top of this post — use the Windows time zone name format (e.g., Eastern Standard Time, not America/New_York).

Why does equals() return false when both values look the same?

Almost always a type mismatch or a case difference. SharePoint columns return typed values — a Yes/No column returns a boolean, not the string "true". Use string() or int() to normalize before comparing, and toLower() when comparing user-entered text. Use a Compose action to inspect both sides individually before debugging the equals() call.

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What's Next

Bookmark this page — it's built to be the one Power Automate expressions reference you keep open in a tab while you write flows, not something you read once and forget.

• Power Automate Document Approval Workflow — end-to-end flow using expressions for dynamic email subjects and conditional routing

• Power Automate HTML Table Styling with CSS — applying expressions to build formatted HTML in flow emails

• Power Platform Custom Connectors REST API Guide — building connectors that consume the JSON outputs your expressions parse

• Microsoft Learn — WDL Functions Reference — the canonical function reference with full parameter specs