# General Translation Platform: formatDateTime
URL: https://generaltranslation.com/en-US/docs/platform/core/reference/utility-functions/formatting/format-date-time.mdx
---

title: formatDateTime
description: Format dates and times without a GT instance. API reference for formatDateTime.

---

[`formatDateTime`](/docs/platform/core/reference/gt-class-methods/formatting/format-date-time) is a standalone utility function from General Translation's Core library that formats dates and times according to locale-specific conventions. It returns a locale-aware string for a `Date`.

## Overview [#overview]

Import `formatDateTime` directly from `generaltranslation` and call it with a `Date` and an options object. It does not require an API key or a [GT](/docs/platform/core/reference/gt-class/constructor) instance. For instance-based formatting that inherits the instance locale, use the [`formatDateTime`](/docs/platform/core/reference/gt-class-methods/formatting/format-date-time) method on a [`GT`](/docs/platform/core/reference/gt-class/constructor) instance instead.

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

const formatted = formatDateTime(new Date(), {
  locales: 'de-DE',
  dateStyle: 'medium',
  timeStyle: 'short',
});
// Returns a locale-formatted string, e.g. "26.09.2025, 17:33"
```

Signature:

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

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

- **Underlying API.** Uses the same [`Intl.DateTimeFormat`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat) as the GT class method, so all standard `Intl.DateTimeFormat` options are supported.
- **Locale resolution.** When `locales` is an array, locales are tried in order. When `locales` is omitted, it falls back to the library default locale, `en`.
- **Time zones.** Output respects the `timeZone` option when provided; otherwise the runtime's local time zone is used. Different locales have different default date/time formats and 12-hour vs. 24-hour preferences.
- **Caching.** Results are cached internally for performance across repeated locale and options combinations.

## Parameters [#parameters]

| Parameter | Description | Type | Optional | Default |
| --- | --- | --- | --- | --- |
| [`date`](#date) | The date object to format. | `Date` | No | — |
| [`options`](#options) | Formatting configuration, including the target locale(s) and any `Intl.DateTimeFormat` options. | `{ locales?: string \| string[] } & Intl.DateTimeFormatOptions` | Yes | `{}` |

### `date` [#date]

**Type** `Date` · **Required**

The `Date` object to format.

### `options` [#options]

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

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.

| Property | Description | Type | Optional | Default |
| --- | --- | --- | --- | --- |
| `locales` | Locale(s) for formatting. Tried in order when an array is passed. | `string \| string[]` | Yes | `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 width for 12-hour cycles. | `'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 date and time formatted according to locale conventions.

## Examples [#examples]

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

const date = new Date('2024-03-14T14:30:45Z');

// Basic formatting with an explicit locale
console.log(formatDateTime(date, { locales: 'en-US', timeZone: 'UTC' }));
// Output: "3/14/2024"

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

// Multiple locale fallbacks
console.log(formatDateTime(date, { locales: ['ja-JP', 'en-US'], timeZone: 'UTC' }));
// Output: "2024/3/14" (Japanese format)
```

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

// Full date style
console.log(formatDateTime(date, {
  locales: 'en-US',
  dateStyle: 'full',
  timeZone: 'UTC',
}));
// Output: "Thursday, March 14, 2024"

// Long date with short time
console.log(formatDateTime(date, {
  locales: 'fr-FR',
  dateStyle: 'long',
  timeStyle: 'short',
  timeZone: 'UTC',
}));
// Output: "14 mars 2024 à 14:30"
```

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

const timeZones = ['America/New_York', 'Europe/London', 'Asia/Tokyo'];

timeZones.forEach((timeZone) => {
  const formatted = formatDateTime(date, {
    locales: 'en-US',
    timeZone,
    dateStyle: 'medium',
    timeStyle: 'medium',
  });
  console.log(`${timeZone}: ${formatted}`);
});
// Output varies based on daylight saving time
```

## Notes [#notes]

- Uses the same underlying `Intl.DateTimeFormat` as the GT class method.
- Results are cached internally for performance with repeated locale/options combinations.
- All standard `Intl.DateTimeFormat` options are supported.
- Time zones are handled correctly when specified. Output without a fixed `timeZone` depends on the runtime environment.