# General Translation Platform: formatDateTime
URL: https://generaltranslation.com/en-US/docs/platform/core/reference/gt-class-methods/formatting/format-date-time.mdx
Docs index: https://generaltranslation.com/llms.txt
Description: Format dates and times by locale. API reference for formatDateTime.

Formats a date and time according to locale-specific conventions on a [GT](/docs/platform/core/reference/gt-class/constructor) instance. General Translation uses the built-in `Intl.DateTimeFormat` API to handle date formats, time formats, calendars, and time zones automatically for the target locale.

## Overview [#overview]

Call `formatDateTime` on a [`GT`](/docs/platform/core/reference/gt-class/constructor) instance with a `Date` and an optional options object. It returns the formatted date and time as a string.

```typescript
const gt = new GT({ targetLocale: 'de-DE' });

const formatted = gt.formatDateTime(new Date(), {
  dateStyle: 'medium',
  timeStyle: 'short',
});
// "25.09.2025, 18:06" (German date/time formatting)
```

Signature:

```typescript
formatDateTime(
  date: Date,
  options?: { locales?: string | string[] } & Intl.DateTimeFormatOptions
): string
```

*Note: `formatDateTime` runs locally using `Intl.DateTimeFormat` and does not require an API key. It uses the instance's target locale by default, then falls back to the source locale and `en`; pass `locales` to override. For formatting without a `GT` instance, see the standalone [`formatDateTime`](/docs/platform/core/reference/utility-functions/formatting/format-date-time).*

## How it works [#how-it-works]

- **Locale resolution.** By default the method formats for the instance's target locale, falling back to the source locale and then `en`. Pass `locales` in the options to override for a single call.
- **Intl-backed.** Formatting is delegated to the browser-native [`Intl.DateTimeFormat`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat), so all standard `Intl.DateTimeFormatOptions` are supported.
- **Time zones.** Time zones are handled correctly when a `timeZone` is specified; otherwise the runtime's local time zone is used.

## Parameters [#parameters]

| Parameter | Description | Type | Optional | Default |
| --- | --- | --- | --- | --- |
| [`date`](#date) | The date object to format. | `Date` | No | — |
| [`options`](#options) | Formatting configuration, extending `Intl.DateTimeFormatOptions` with a `locales` override. | `object` | Yes | — |

### `date` [#date]

**Type** `Date` · **Required**

The `Date` object to format.

### `options` [#options]

**Type** `{ locales?: string | string[] } & Intl.DateTimeFormatOptions` · **Optional**

Formatting configuration. The table lists common options exposed by the published Core types and their effective Core defaults. (See the [`Intl.DateTimeFormat` constructor options](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat/DateTimeFormat#options) for supplemental standard and runtime-specific details).

| Name | Description | Type | Optional | Default |
| --- | --- | --- | --- | --- |
| `locales` | Override locales for formatting. | `string \| string[]` | Yes | `targetLocale` → `sourceLocale` → `en` |
| `localeMatcher` | Locale matching algorithm. | `'lookup' \| 'best fit'` | Yes | `'best fit'` |
| `dateStyle` | Overall date formatting style. | `'full' \| 'long' \| 'medium' \| 'short'` | Yes | — |
| `timeStyle` | Overall time formatting style. | `'full' \| 'long' \| 'medium' \| 'short'` | Yes | — |
| `weekday` | Weekday representation. | `'long' \| 'short' \| 'narrow'` | Yes | — |
| `era` | Era representation. | `'long' \| 'short' \| 'narrow'` | Yes | — |
| `year` | Year representation. | `'numeric' \| '2-digit'` | Yes | `'numeric'` when no styles or components are set |
| `month` | Month representation. | `'numeric' \| '2-digit' \| 'long' \| 'short' \| 'narrow'` | Yes | `'numeric'` when no styles or components are set |
| `day` | Day representation. | `'numeric' \| '2-digit'` | Yes | `'numeric'` when no styles or components are set |
| `dayPeriod` | Day period formatting (morning, afternoon, etc.). | `'narrow' \| 'short' \| 'long'` | Yes | — |
| `hour` | Hour representation. | `'numeric' \| '2-digit'` | Yes | — |
| `minute` | Minute representation. | `'numeric' \| '2-digit'` | Yes | — |
| `second` | Second representation. | `'numeric' \| '2-digit'` | Yes | — |
| `fractionalSecondDigits` | Number of fractional second digits. | `1 \| 2 \| 3` | Yes | — |
| `timeZoneName` | Time zone name format. | `'long' \| 'short' \| 'longOffset' \| 'shortOffset' \| 'longGeneric' \| 'shortGeneric'` | Yes | — |
| `timeZone` | IANA time zone name or supported UTC offset identifier. | `string` | Yes | runtime time zone |
| `hour12` | Whether to use 12-hour time format. | `boolean` | Yes | locale-dependent |
| `hourCycle` | Hour cycle preference. | `'h11' \| 'h12' \| 'h23' \| 'h24'` | Yes | locale-dependent |
| `calendar` | Calendar system to use. | `string` | Yes | `'gregory'` |
| `numberingSystem` | Numbering system for digits. | `string` | Yes | `'latn'` |
| `formatMatcher` | Format matching algorithm. | `'basic' \| 'best fit'` | Yes | `'best fit'` |

`dateStyle` and `timeStyle` can be combined with each other, but not with individual date-time component options such as `year`, `month`, or `hour`. `hour12` overrides `hourCycle`, and `dayPeriod` only affects 12-hour cycles. Core sets `calendar: 'gregory'` and `numberingSystem: 'latn'`; upstream `Intl.DateTimeFormat` otherwise chooses both from the locale.

## Returns [#returns]

**Type** `string`

The formatted date and time, following the target locale's conventions.

## Examples [#examples]

*Note: examples without an explicit `timeZone` render in the runtime's local time zone; the time-of-day outputs below assume `America/Los_Angeles` (UTC−7 on this date).*

```typescript
import { GT } from 'generaltranslation';

const gt = new GT({ targetLocale: 'en-US' });
const date = new Date('2024-03-14T14:30:45Z');

// Basic date formatting (uses default options)
console.log(gt.formatDateTime(date));
// Output: "3/14/2024"

// German locale formatting
console.log(gt.formatDateTime(date, { locales: 'de-DE' }));
// Output: "14.3.2024"

// Japanese locale formatting
console.log(gt.formatDateTime(date, { locales: 'ja-JP' }));
// Output: "2024/3/14"
```

```typescript
// Date and time styles
const date = new Date('2024-03-14T14:30:45Z');

// Full date style
console.log(gt.formatDateTime(date, { dateStyle: 'full' }));
// Output: "Thursday, March 14, 2024"

// Long date with short time
console.log(gt.formatDateTime(date, {
  dateStyle: 'long',
  timeStyle: 'short',
}));
// Output: "March 14, 2024 at 7:30 AM"

// Custom date components
console.log(gt.formatDateTime(date, {
  weekday: 'long',
  year: 'numeric',
  month: 'long',
  day: 'numeric',
}));
// Output: "Thursday, March 14, 2024"
```

```typescript
// Time zone and hour format
const date = new Date('2024-03-14T14:30:45Z');

// Force 12-hour format
console.log(gt.formatDateTime(date, {
  hour: 'numeric',
  minute: '2-digit',
  hour12: true,
}));
// Output: "7:30 AM"

// Force 24-hour format
console.log(gt.formatDateTime(date, {
  hour: 'numeric',
  minute: '2-digit',
  hour12: false,
}));
// Output: "07:30"

// Specific time zone
console.log(gt.formatDateTime(date, {
  timeZone: 'America/New_York',
  dateStyle: 'medium',
  timeStyle: 'short',
}));
// Output: "Mar 14, 2024, 10:30 AM"
```

## Notes [#notes]

- Date formatting follows locale-specific conventions automatically.
- The method uses browser-native `Intl.DateTimeFormat` for performance and accuracy.
- Time zones are handled correctly when specified.

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