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

npm install pretty-ms

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'

Type: number | bigint

Milliseconds to humanize.

Type: object

Type: number
Default: 1

Number of digits to appear after the seconds decimal point.

Type: number
Default: 0

Number of digits to appear after the milliseconds decimal point.

Useful in combination with process.hrtime().

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.

Type: boolean
Default: false

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

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

Type: number
Default: Infinity

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

Type: boolean
Default: false

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

Type: boolean
Default: false

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

Type: boolean
Default: false

Show microseconds and nanoseconds.

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

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.

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.

Type: boolean
Default: false

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

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.

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 or a date library like date-fns.

• pretty-ms-cli - CLI for this module
• parse-ms - Parse milliseconds into an object
• to-milliseconds - Convert an object of time properties to milliseconds
• pretty-bytes - Convert bytes to a human readable string