# Native Temporal and GMT

GMT is built on `@js-temporal/polyfill`, so it runs on a runtime that has no native Temporal. This page lists where Temporal is native and which GMT function matches each Temporal call.

## Where Temporal runs

Checked 2026-10-26, from the MDN browser compatibility data.

| Runtime | First version with Temporal |
| --- | --- |
| Chrome and Edge | 144 |
| Firefox | 139 |
| Node.js | 26 |
| Deno | 2.7 |
| Bun | 1.4.0 |
| Safari on macOS | Technology Preview only |
| Safari on iOS | not supported |

## Status of the specification

TC39 moved Temporal to Stage 4 on 2026-03-11. It is not yet part of ECMA-262. On 2026-10-26 the pull request that adds it, [ecma262 #3966](https://github.com/tc39/ecma262/pull/3966), was open. An earlier pull request, #3759, was closed without merging. The text of the proposal is at [tc39.es/proposal-temporal](https://tc39.es/proposal-temporal/), and the clause numbers below refer to it.

## Temporal call to GMT function

| Task | Temporal | GMT | Specification |
| --- | --- | --- | --- |
| Today in a zone | `Temporal.Now.plainDateISO(z).toString()` | `getZonedToday` | [2.2.5](https://tc39.es/proposal-temporal/#sec-temporal.now.plaindateiso) |
| Now in a zone | `Temporal.Now.zonedDateTimeISO(z).toString()` | `getZonedNow` | [2.2.4](https://tc39.es/proposal-temporal/#sec-temporal.now.zoneddatetimeiso) |
| Now as UTC | `Temporal.Now.instant().toString()` | `getUtcNow` | [2.2.2](https://tc39.es/proposal-temporal/#sec-temporal.now.instant) |
| Add a month | `PlainDate.from(s).add({ months: 1 }).toString()` | `addDate` | [3.3.21](https://tc39.es/proposal-temporal/#sec-temporal.plaindate.prototype.add), [3.5.7](https://tc39.es/proposal-temporal/#sec-temporal-regulateisodate) |
| Add a calendar day in a zone | `ZonedDateTime.from(s).add({ days: 1 })` | `addZoned` | [6.3.35](https://tc39.es/proposal-temporal/#sec-temporal.zoneddatetime.prototype.add), [6.5.5](https://tc39.es/proposal-temporal/#sec-temporal-addzoneddatetime) |
| Difference | `a.until(b, { largestUnit: "months" })` | `diffDate` | [3.3.25](https://tc39.es/proposal-temporal/#sec-temporal.plaindate.prototype.until), [12.3.9](https://tc39.es/proposal-temporal/#sec-temporal-calendardateuntil) |
| Start of day | `zdt.startOfDay()` | `startOfZoned` | [6.3.45](https://tc39.es/proposal-temporal/#sec-temporal.zoneddatetime.prototype.startofday), [11.1.14](https://tc39.es/proposal-temporal/#sec-temporal-getstartofday) |
| Hours in a day | `zdt.hoursInDay` | `getHoursInZonedDay` | [6.3.23](https://tc39.es/proposal-temporal/#sec-get-temporal.zoneddatetime.prototype.hoursinday) |
| Change zone | `zdt.withTimeZone(z)` | `convertZonedToZoned` | [6.3.33](https://tc39.es/proposal-temporal/#sec-temporal.zoneddatetime.prototype.withtimezone) |
| UTC to zone | `Instant.from(u).toZonedDateTimeISO(z)` | `convertUtcToZoned` | [8.3.15](https://tc39.es/proposal-temporal/#sec-temporal.instant.prototype.tozoneddatetimeiso) |
| Wall time to zone | `PlainDateTime.from(l).toZonedDateTime(z, { disambiguation })` | `convertPlainDateTimeToZoned` | [5.3.38](https://tc39.es/proposal-temporal/#sec-temporal.plaindatetime.prototype.tozoneddatetime), [11.1.11](https://tc39.es/proposal-temporal/#sec-temporal-getepochnanosecondsfor) |
| Does the wall time exist | No public method; the specification counts the candidate instants | `classifyLocal` | [11.1.13](https://tc39.es/proposal-temporal/#sec-temporal-getpossibleepochnanoseconds) |
| Next transition | `zdt.getTimeZoneTransition("next")` | `getDstTransitions` | [6.3.46](https://tc39.es/proposal-temporal/#sec-temporal.zoneddatetime.prototype.gettimezonetransition) |
| Round | `zdt.round({ smallestUnit: "hour" })` | `roundZoned` | [6.3.39](https://tc39.es/proposal-temporal/#sec-temporal.zoneddatetime.prototype.round) |
| Equal values | `a.equals(b)` | `areZonedEqual` | [6.3.40](https://tc39.es/proposal-temporal/#sec-temporal.zoneddatetime.prototype.equals) |
| ISO week | `d.yearOfWeek`, `d.weekOfYear`, `d.dayOfWeek` | `getIsoWeekDate` | [3.3.12](https://tc39.es/proposal-temporal/#sec-get-temporal.plaindate.prototype.weekofyear), [3.3.13](https://tc39.es/proposal-temporal/#sec-get-temporal.plaindate.prototype.yearofweek), [12.3.18](https://tc39.es/proposal-temporal/#sec-temporal-isoweekofyear) |
| Change calendar | `d.withCalendar("japanese")` | `convertDateToCalendar` | [3.3.24](https://tc39.es/proposal-temporal/#sec-temporal.plaindate.prototype.withcalendar) |
| A year and a month | `PlainYearMonth.from(s).toString()` | `parseYearMonth`, `isValidYearMonth` | [9.2.2](https://tc39.es/proposal-temporal/#sec-temporal.plainyearmonth.from) |
| A month and a day | `PlainMonthDay.from(s).toString()` | `parseMonthDay`, `isValidMonthDay` | [10.2.2](https://tc39.es/proposal-temporal/#sec-temporal.plainmonthday.from) |
| A month-day in a year | `md.toPlainDate({ year })` | `monthDayToDate` | [10.3.12](https://tc39.es/proposal-temporal/#sec-temporal.plainmonthday.prototype.toplaindate) |
| Duration total | `Duration.from(s).total({ unit, relativeTo })` | `totalDuration` | [7.3.21](https://tc39.es/proposal-temporal/#sec-temporal.duration.prototype.total) |
| A `Date` object | `date.toTemporalInstant()` | `toTemporalInstant` | [14.9.1](https://tc39.es/proposal-temporal/#sec-date.prototype.totemporalinstant) |

The clause in each row is the rule GMT follows for that call.

## Using both from one import

GMT re-exports `Temporal`, `Intl` and `toTemporalInstant` from its root, taken from the polyfill. Code that needs a Temporal object and a GMT function can take both from `@northguild/gmt`.

```js
import { Temporal, toTemporalInstant } from "@northguild/gmt";
```

For the results other libraries return on the same inputs, see [Behaviour of date libraries against Temporal](/gmt/compare/behaviour/). Each library has its own page: [date-fns](/gmt/migrate/date-fns/), [Luxon](/gmt/migrate/luxon/), [Day.js](/gmt/migrate/dayjs/), [Moment.js](/gmt/migrate/moment/) and [@internationalized/date](/gmt/migrate/internationalized-date/).