Date Variables

CoreCategory30 Variables

Time is a segmentation axis, a compliance requirement, and an attribution signal — all at once. Fire tags only during business hours. Send Meta CAPI the Unix timestamp it demands. Calculate lead time from form to purchase. Convert dates between every system that speaks a different format. Date is the category that makes time behave — 30 sandbox-safe variable templates for dayparting, timestamps, format conversion, and duration math. No Custom JavaScript.

30 variables100% sandbox-safeWeb + ServerMIT licensed

Why this category exists

Every GTM container handles time somewhere. Some tags need to fire only at specific times of day. Some destinations require Unix timestamps in a specific unit. Some dataLayer values arrive as dates in the wrong format. Some attribution reports need duration math between events. These are separate problems with the same substrate — and almost every implementation solves them with one-off Custom JavaScript that nobody maintains.

The Date category covers four jobs:

Dayparting and time-based triggers. Fire tags only during business hours, only on weekends, only in specific hour windows. Currently solved with new Date().getHours() in Custom JavaScript — code that lives in one place but whose rules need to change seasonally.
Timestamps for destination compliance. Meta CAPI requires event_time in Unix seconds. Some server endpoints want milliseconds. Event deduplication between pixel and CAPI needs the same timestamp in both tags.
Duration math. Lead time from form to purchase, days since first visit, time between engagement and conversion. Feeds attribution analysis and can be sent as a Smart Bidding signal.
Format and unit conversion. CRM pushes “25/12/2024”, data warehouse expects “2024-12-25”, internal system uses “20241225”. Engagement time in milliseconds, GA4 wants seconds.

All four jobs have clean named-template solutions. No Custom JavaScript required for any of them.

The dataLayer date problem

Dates arrive in the dataLayer — and from DOM scraping, cookies, and third-party systems — in every format except the one you want:

Format A

ISO extended

”2024-12-25”

Format B

ISO basic (compact)

“20241225”

Format C

European slash

”25/12/2024”

Format D

US slash

”12/25/2024”

Format E

Unix milliseconds

1735084800000

Format F

Unix seconds

1735084800

Every one of these shows up in real containers — often more than one simultaneously, because different parts of the stack (backend, CRM, analytics) standardize on different conventions. The Date category doesn’t care which you start with; there’s a variable to move between any pair.

The variables — at a glance

Twenty-nine variables, grouped by the job they do. The Business time group is the hero — variables that turn timestamps into segmentation, attribution, and compliance signals.

Business time — segmentation, duration, compliance

isBusinessHoursBoolean: is current time in the configured business-hour window?isWeekendBoolean: is the current day a weekend day?getHourOfDayCurrent hour (0-23) or hour extracted from a timestamp.calculateLeadTimeDuration between two events (form → purchase, signup → order).calculateDaysDifferenceNumber of days between two dates.currentTimestampCurrent Unix timestamp in milliseconds.addDaysAdd (or subtract) days from a date. Negative values go back in time.

Component extraction

getDayNameFull day name from current date — “Monday”.getDayNameShortShort day name — “Mon”.getDayNameFromDateStringDay name extracted from a date string input.getDayIndexFromDateStringNumeric day index (0 = Sunday) from a date string.timestampToDayIndexDay index from a Unix timestamp.getMonthNameFull month name — “December”.getMonthNameShortShort month name — “Dec”.

Format conversion

basicDateToExtendedYYYYMMDD → YYYY-MM-DD (ISO basic to extended).extendedDateToBasicYYYY-MM-DD → YYYYMMDD (ISO extended to basic).reverseDateSlashSwap MM/DD/YYYY and DD/MM/YYYY.reverseDateCompactDay1stReorder a compact date to day-first.reverseDateCompactYear1stReorder a compact date to year-first.

Timestamp conversion

dateToUnixTimestampConvert a date string to Unix timestamp.unixTimestampToDateConvert a Unix timestamp to a readable date string.

Unit conversion

millisecondsToSecondsms → s. Required for Meta CAPI event_time.secondsToMillisecondss → ms.millisecondsToMinutesms → minutes.minutesToMillisecondsMinutes → ms.millisecondsToHoursms → hours.hoursToMillisecondsHours → ms.millisecondsToDaysms → days.daysToMillisecondsDays → ms.

Fire tags during business hours only

Service-focused campaigns often should run only when someone is available to answer the phone. B2B lead generation during working hours, e-commerce chat triggers when support is live, remarketing tags that match when a physical store is open.

Recipe — Business-hours trigger condition

Variable: isBusinessHours · Direct mode · Use as trigger condition

Field	Value
Start hour (24h)	`9`
End hour (24h)	`18`
Business days	`Monday-Friday`
Timezone	`browser` (or specify e.g. `Europe/Paris`)

→ true between 9:00 and 18:00 local time on weekdays; false otherwise

Add the variable as a trigger condition with isBusinessHours equals true to gate tag firing. To fire a different tag outside business hours (e.g., a “contact us tomorrow” notice), use isBusinessHours equals false on a parallel trigger.

Timezone gotcha. By default, isBusinessHours uses the browser timezone, which means a user in Tokyo hitting a French business’s site during Paris business hours will see “closed.” If your business operates in a specific timezone and you want that perspective globally, set the timezone parameter explicitly.

Fire tags only on weekdays or weekends

Weekend promotions, weekday-only B2B campaigns, Tuesday-specific flash sales — day-of-week targeting is one of the most common segmentation patterns in marketing.

Recipe — Weekend-only tag trigger

Variable: isWeekend · Direct mode · Use as trigger condition

Field	Value
Weekend days	`Saturday, Sunday` (configurable for Middle East markets where Friday-Saturday)
Timezone	`browser` or explicit

→ true on weekend days; false on weekdays

For specific-day targeting, use getDayIndexFromDateString and compare to the numeric index (0 = Sunday, 1 = Monday, through 6 = Saturday). Example trigger condition: getDayIndexFromDateString equals 2 fires only on Tuesdays.

Segment by hour of day (dayparting)

Hour-of-day segmentation goes deeper than business hours — you might want a GA4 custom dimension tracking “morning / afternoon / evening / night” visitor behavior, or a specific tag that fires only during prime-time ad slots (18:00-22:00).

Recipe — Classify current hour into daypart

Variables: getHourOfDay (Apply) → classifyByThreshold (Direct)

Field	Value
getHourOfDay output	Integer 0-23
classifyByThreshold thresholds	`[6, 12, 18, 22]`
classifyByThreshold labels	`[“night”, “morning”, “afternoon”, “evening”, “late_night”]`

→ 14 (2pm) becomes “afternoon”, ready as GA4 custom dimension value

The classified daypart value can feed a GA4 custom dimension, a Google Ads conversion parameter, or a trigger condition. Pair with isWeekend for a combined daypart × weekday/weekend matrix.

Calculate lead time between two events

Lead time — the duration between two events for the same user — is an attribution signal that most containers don’t capture. The form submission that converts within 24 hours is a hotter lead than the one that converts after 14 days.

Recipe — Lead time from form submission to purchase

Variable: calculateLeadTime · Direct or Apply mode

Field	Value
Start timestamp	`{{Cookie - lead_form_timestamp}}`
End timestamp	`{{Apply - currentTimestamp}}`
Output unit	`days` (or `hours`, `minutes`)

→ If the form was submitted 3.5 days ago, returns 3.5 (or 84 in hours)

The result is a number you can send as a custom parameter on the conversion event. Advanced: use the lead-time value as an input to a scoring pipeline where shorter lead time increases the conversion value sent to Smart Bidding.

calculateLeadTimeApply→scaleToRangeApply→Google Ads conversion value

Calculate days between two dates

”Days since first visit,” “days until campaign end,” “days since last purchase for reactivation” — all variations of the same calculation.

Recipe — Days since first visit

Variable: calculateDaysDifference · Direct or Apply mode

Field	Value
Start date	`{{Cookie - first_visit_date}}`
End date	`{{Apply - currentTimestamp}}`

→ Number of days between the two dates

Bucket the result with classifyByThreshold to produce tiered segments: “new” (0-7 days), “returning” (8-30), “dormant” (31+).

Add Unix timestamps to Meta CAPI events

Meta’s Conversions API requires event_time in Unix seconds on every event. Omit it and the event fails. Send it in milliseconds by mistake and the timestamp resolves to the year 55000-something — Meta accepts the event but its attribution is broken.

Source — Meta Conversions API

”A Unix timestamp in seconds indicating when the actual event occurred. You must send this date in GMT time zone.”

developers.facebook.com — Conversions API parameters

Recipe — event_time for Meta CAPI

Variables: currentTimestamp (Apply) → millisecondsToSeconds (Direct)

Field	Value
currentTimestamp output	Unix ms — `1735084800000`
millisecondsToSeconds output	Unix s — `1735084800`

→ Use the final variable as event_time in the Meta CAPI tag

For event deduplication between the browser pixel and CAPI, both tags must send the same event_time. Reference the same variable from both, and pair with an event_id (typically from randomInteger).

Convert date formats between CRM and warehouse

Multi-system tracking runs into a universal problem: CRM sends “25/12/2024”, data warehouse expects “2024-12-25”, analytics system stores “20241225”.

Recipe — European slash date to ISO extended

Variables: reverseDateSlash (Apply) → replace (Direct, slashes to dashes)

Field	Value
Input	`”25/12/2024”` (DD/MM/YYYY)
After reverseDateSlash	`”2024/12/25”`
After replace /→-	`“2024-12-25”`

→ ISO-compliant date string ready for a warehouse or BigQuery export

For the simplest format swap — ISO basic to extended — basicDateToExtended is the single-variable answer: “20241225” becomes “2024-12-25” directly. Use extendedDateToBasic for the reverse.

Convert engagement milliseconds to GA4-ready units

Browser APIs return durations in milliseconds. performance.now(), custom timing marks, video playback duration. GA4’s engagement time parameters expect seconds.

Recipe — Convert raw engagement ms to seconds for GA4

Variable: millisecondsToSeconds · Direct or Apply mode

Field	Value
Input	`{{DL - engagement_ms}}` — e.g. `45000`

→ 45 (seconds) ready for the GA4 event parameter

The unit-conversion pair set (millisecondsToSeconds, millisecondsToMinutes, millisecondsToHours, millisecondsToDays and their reverses) covers every direction. Chain toFixedNumber downstream for specific decimal precision.

Extract readable month and day names

Reports read better with month and day names than numbers. “December” in a GA4 custom dimension is more useful than 12.

Recipe — Month name for GA4 custom dimension

Variable: getMonthName · Direct mode

Field	Value
Source	`current date` (default) or configurable input date
Locale	`en-US`, `fr-FR`, `de-DE`, etc.

→ “December” in English, “décembre” in French, “Dezember” in German

For charts with limited horizontal space, use getMonthNameShort (“Dec”) and getDayNameShort (“Mon”).

Convert Unix timestamps back to readable dates

Cookies and backend systems frequently store timestamps as Unix numbers — but for display in GA4 custom dimensions you need a readable date.

Recipe — Cookie timestamp to readable date

Variable: unixTimestampToDate · Direct or Apply mode

Field	Value
Input	`{{Cookie - first_visit_ts}}` — Unix seconds or ms
Output format	`YYYY-MM-DD` (ISO) or configurable

→ 1735084800 becomes “2024-12-25”

For just the day-of-week component, use timestampToDayIndex — a fast direct path that avoids the full date conversion when you only need 0-6.

Add or subtract days from a date

Campaign end dates, subscription renewal calculations, “next available date” logic — all need date arithmetic. addDays handles forward and backward moves (negative values go back in time).

Recipe — Calculate campaign end date from start date

Variable: addDays · Direct or Apply mode

Field	Value
Source date	`{{DL - campaign_start_date}}`
Days to add	`30`

→ “2024-12-01” + 30 days = “2024-12-31”

For “7 days ago from now,” use addDays with input currentTimestamp and days -7. Combine with calculateDaysDifference to build recency/frequency segmentation entirely in the container.

Composed patterns — chaining variables

Four chains that cover most real-world date pipelines:

Meta CAPI event_time

Current time in Unix seconds, ready for the CAPI event_time parameter.

currentTimestampApply→millisecondsToSecondsDirect

Dayparting for GA4 custom dimension

Current hour classified into a named daypart, ready as a dimension value.

getHourOfDayApply→classifyByThresholdDirect

Lead-time conversion value

Lead time converted to a Smart Bidding signal where shorter = higher conversion value.

calculateLeadTimeApply→clampApply→scaleToRangeDirect

CRM-to-warehouse date normalization

European slash date converted to ISO extended format for a data warehouse export.

reverseDateSlashApply→replaceDirect

Why you don’t need Custom JavaScript

Every tutorial on date handling in GTM eventually arrives at a variation of the same pattern:

function() {
var now = new Date();
var hour = now.getHours();
var day = now.getDay();
if (day === 0 || day === 6) return false;
if (hour < 9 || hour >= 18) return false;
return true;
}

Or worse:

function() {
var parts = {{DLV - date_str}}.split(’/’);
var iso = parts[2] + ’-’ + parts[1] + ’-’ + parts[0];
return iso;
}

Works until it doesn’t. The first breaks silently in timezone edge cases. The second breaks the day someone pushes “12-25-2024” with dashes instead of slashes. The variable name is cjs - biz_hrs and nobody remembers whether it accounts for holidays.

Named templates replace the whole pattern:

Intent in the name. isBusinessHours means exactly one thing. cjs - biz_hrs means whatever the code inside happens to do.
Configuration lives in the UI. Changing business hours for daylight savings means editing a variable config, not code.
Format handling is centralized. The day someone discovers reverseDateSlash doesn’t handle a new CRM format, you fix it once and every container importing it picks up the fix.
Server-side portability. sGTM’s stricter sandbox accepts named templates that ad-hoc Custom JavaScript wouldn’t.

Cheatsheet

Goal	Variable	Mode
Fire tag only during business hours	`isBusinessHours`	Direct
Fire tag only on weekends / weekdays	`isWeekend`	Direct
Extract current hour (0-23)	`getHourOfDay`	Direct / Apply
Lead time between two events	`calculateLeadTime`	Direct / Apply
Days between two dates	`calculateDaysDifference`	Direct / Apply
Current Unix timestamp (ms)	`currentTimestamp`	Direct / Apply
Add or subtract days from a date	`addDays`	Direct / Apply
Full / short day name	`getDayName` / `getDayNameShort`	Direct
Day name from date string input	`getDayNameFromDateString`	Apply
Numeric day index (0 = Sunday)	`getDayIndexFromDateString` / `timestampToDayIndex`	Apply
Full / short month name	`getMonthName` / `getMonthNameShort`	Direct
ISO basic ↔ extended (YYYYMMDD ↔ YYYY-MM-DD)	`basicDateToExtended` / `extendedDateToBasic`	Apply
Swap date component order	`reverseDateSlash` / `reverseDateCompact*`	Apply
Date ↔ Unix timestamp	`dateToUnixTimestamp` / `unixTimestampToDate`	Apply
ms ↔ seconds	`millisecondsToSeconds` / `secondsToMilliseconds`	Apply
ms ↔ minutes / hours / days	`millisecondsToMinutes`, etc.	Apply

FAQ

How do I fire a GTM tag only during business hours?

Use isBusinessHours as a trigger condition. Configure the start hour, end hour, business days, and timezone. The variable returns true when the current time falls within the defined window, false otherwise.

How do I fire a tag only on weekdays or weekends?

isWeekend returns a boolean. Use as a trigger condition with equals true for weekend-only or equals false for weekday-only tags. For specific days, use getDayIndexFromDateString and compare to the numeric index (0 = Sunday, 1 = Monday, etc.).

How do I calculate lead time between a form submission and a purchase?

Store the form submission timestamp in a cookie. On the purchase event, read the stored timestamp and pass it with currentTimestamp to calculateLeadTime. Returns the duration in days (or configurable units). Send as a custom parameter on the conversion event.

How do I add a Unix timestamp to a Meta CAPI event?

Meta CAPI requires event_time in Unix seconds. Use currentTimestamp to get milliseconds, then chain millisecondsToSeconds. For event deduplication between the browser pixel and CAPI, reference the same variable in both tags.

How do I convert date formats between systems?

reverseDateSlash, reverseDateCompactDay1st, and reverseDateCompactYear1st handle common format swaps. basicDateToExtended converts YYYYMMDD to YYYY-MM-DD; extendedDateToBasic does the reverse. Chain them to normalize dates between CRM, warehouse, and analytics.

How do I extract the day of week?

getDayName returns a full name like “Monday”. getDayNameShort returns “Mon”. getDayIndexFromDateString returns the numeric index (0 = Sunday through 6 = Saturday) for comparison logic. Use the FromDateString variants when parsing from a date string input.

Are these variables sandbox-safe in server-side GTM?

Yes. All templates run inside GTM’s sandboxed JavaScript environment using only permissioned APIs. They work in web and server containers.