# pretty-ms

> Convert milliseconds to a human readable string: `1337000000` → `15d 11h 23m 20s`

Latest version **9.3.1** (published 2026-08-28) · MIT license · 0 weekly downloads

## Install

```sh
npm install pretty-ms
pnpm add pretty-ms
yarn add pretty-ms
bun add pretty-ms
```

## Health

**Score 70/100 (B)** — status: active.

Positive: has types; esm support; no vulnerabilities; recently updated; high maintenance score; high quality score.

Warnings: low downloads.

## Facts

| | |
|---|---|
| Version | 9.3.1 |
| Published | 2026-08-28 |
| First published | 2014-03-20 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | bundled |
| Module format | ESM |
| Node | >=18 |
| Dependencies | 1 |
| Unpacked size | 15.3 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 1215 |
| Author | Sindre Sorhus |
| Maintainers | sindresorhus |
| Keywords | pretty, prettify, human, humanize, humanized, readable, time, ms, milliseconds, duration, period, range, text, string, number, hrtime |

## Links

- npm: https://www.npmjs.com/package/pretty-ms
- Repository: https://github.com/sindresorhus/pretty-ms
- Homepage: https://github.com/sindresorhus/pretty-ms#readme
- Issues: https://github.com/sindresorhus/pretty-ms/issues
- Funding: https://github.com/sponsors/sindresorhus
- npm.io page: https://npm.io/package/pretty-ms

## Dependencies (1)

- [parse-ms](https://npm.io/package/parse-ms.md) ^4.0.0

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## Recent versions

- 9.3.1 (latest) — 2026-08-28
- 9.3.0 — 2025-09-15
- 9.2.0 — 2024-11-15
- 9.1.0 — 2024-07-23
- 9.0.0 — 2024-01-18
- 8.0.0 — 2022-06-06
- 7.0.1 — 2020-09-24
- 7.0.0 — 2020-04-27
- 6.0.1 — 2020-03-02
- 6.0.0 — 2020-02-12
- 5.1.0 — 2019-11-22
- 5.0.0 — 2019-04-24
- 4.0.0 — 2018-09-18
- 3.2.0 — 2018-05-25
- 3.1.0 — 2017-11-20
- … 14 more at https://npm.io/package/pretty-ms/versions

## README

# pretty-ms

> Convert milliseconds to a human readable string: `1337000000` → `15d 11h 23m 20s`

*See [`parse-duration-ms`](https://github.com/sindresorhus/parse-duration-ms) for the inverse.*

## Install

```sh
npm install pretty-ms
```

## Usage

```js
import prettyMilliseconds from 'pretty-ms';

prettyMilliseconds(1337000000);
//=> '15d 11h 23m 20s'

prettyMilliseconds(1337000000n);
//=> '15d 11h 23m 20s'

prettyMilliseconds(1337);
//=> '1.3s'

prettyMilliseconds(133);
//=> '133ms'

// `compact` option
prettyMilliseconds(1337, {compact: true});
//=> '1s'

// `verbose` option
prettyMilliseconds(1335669000, {verbose: true});
//=> '15 days 11 hours 1 minute 9 seconds'

// `colonNotation` option
prettyMilliseconds(95500, {colonNotation: true});
//=> '1:35.5'

// `formatSubMilliseconds` option
prettyMilliseconds(100.400080, {formatSubMilliseconds: true})
//=> '100ms 400µs 80ns'

// `subSecondsAsDecimals` option
prettyMilliseconds(900, {subSecondsAsDecimals: true});
//=> '0.9s'

// Can be useful for time durations
prettyMilliseconds(new Date(2014, 0, 1, 10, 40) - new Date(2014, 0, 1, 10, 5))
//=> '35m'
```

## API

### prettyMilliseconds(milliseconds, options?)

#### milliseconds

Type: `number | bigint`

Milliseconds to humanize.

#### options

Type: `object`

##### secondsDecimalDigits

Type: `number`\
Default: `1`

Number of digits to appear after the seconds decimal point.

##### millisecondsDecimalDigits

Type: `number`\
Default: `0`

Number of digits to appear after the milliseconds decimal point.

Useful in combination with [`process.hrtime()`](https://nodejs.org/api/process.html#process_process_hrtime_time).

##### keepDecimalsOnWholeSeconds

Type: `boolean`\
Default: `false`

Keep milliseconds on whole seconds: `13s` → `13.0s`.

Useful when you are showing a number of seconds spent on an operation and don't want the width of the output to change when hitting a whole number.

##### compact

Type: `boolean`\
Default: `false`

Only show the first unit: `1h 10m` → `1h`.

Also ensures that `millisecondsDecimalDigits` and `secondsDecimalDigits` are both set to `0`.

##### unitCount

Type: `number`\
Default: `Infinity`

Number of units to show. Setting `compact` to `true` overrides this option.

##### verbose

Type: `boolean`\
Default: `false`

Use full-length units: `5h 1m 45s` → `5 hours 1 minute 45 seconds`

##### separateMilliseconds

Type: `boolean`\
Default: `false`

Show milliseconds separately. This means they won't be included in the decimal part of the seconds.

##### formatSubMilliseconds

Type: `boolean`\
Default: `false`

Show microseconds and nanoseconds.

##### colonNotation

Type: `boolean`\
Default: `false`

Display time using colon notation: `5h 1m 45s` → `5:01:45`. Always shows time in at least minutes: `1s` → `0:01`

Useful when you want to display time without the time units, similar to a digital watch.

Setting `colonNotation` to `true` overrides the following options to `false`:
- `compact`
- `formatSubMilliseconds`
- `separateMilliseconds`
- `verbose`

##### hideYear

Type: `boolean`\
Default: `false`

Hides the year and shows the hidden year additionally as days (365 per year): `1y 3d 5h 1m 45s` → `368d 5h 1m 45s`.

##### hideYearAndDays

Type: `boolean`\
Default: `false`

Hides the year and days and shows the hidden values additionally as hours: `1y 3d 5h 1m 45s` → `8837h 1m 45s`.

##### hideSeconds

Type: `boolean`\
Default: `false`

Hides the seconds: `1y 3d 5h 1m 45s` → `1y 3d 5h 1m`.

##### subSecondsAsDecimals

Type: `boolean`\
Default: `false`

Show sub-second values as decimal seconds: `900ms` → `0.9s`.

Useful for progress indicators where you want consistent unit format to prevent flickering.

## FAQ

### Why doesn't this package support months or years?

This package formats time durations, not calendar dates. Months (28-31 days) and years (365-366 days) have variable lengths, making duration calculations ambiguous. Days are the largest unit since they're always exactly 24 hours. For calendar-based formatting, use [Temporal API](https://tc39.es/proposal-temporal/docs/) or a date library like [date-fns](https://github.com/date-fns/date-fns).

### Why doesn't the formatted difference of two values match the formatted values?

```js
prettyMilliseconds(3670);        //=> '3.6s'
prettyMilliseconds(5230);        //=> '5.2s'
prettyMilliseconds(5230 - 3670); //=> '1.5s' // Not '1.6s'
```

This is inherent to displaying rounded numbers, the same reason [rounded percentages don't always add up to 100%](https://help.surveymonkey.com/en/surveymonkey/analyze/percents-not-totaling/). Values are rounded independently, and rounding does not distribute over subtraction. `prettyMilliseconds(5230 - 3670)` correctly represents the true difference; it just won't always match subtracting the two rounded strings by eye.

## Related

- [pretty-ms-cli](https://github.com/sindresorhus/pretty-ms-cli) - CLI for this module
- [parse-ms](https://github.com/sindresorhus/parse-ms) - Parse milliseconds into an object
- [to-milliseconds](https://github.com/sindresorhus/to-milliseconds) - Convert an object of time properties to milliseconds
- [parse-duration-ms](https://github.com/sindresorhus/parse-duration-ms) - Parse duration strings to milliseconds
- [pretty-bytes](https://github.com/sindresorhus/pretty-bytes) - Convert bytes to a human readable string

---
_Source: https://npm.io/package/pretty-ms · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._