UnitFormat.js

UnitFormat.js is a number formatter for human readable unit numbers, like 10km, 5GB, 17kHz, 220MW, ... with known metric suffixes.

Installation

You can install UnitFormat.js via npm:

npm install unitformat

Or with yarn:

yarn add unitformat

Alternatively, download or clone the repository:

git clone https://github.com/rawify/UnitFormat.js

Usage

Include the unitformat.min.js file in your project:

<script src="path/to/unitformat.min.js"></script>
<script>
  var x = UnitFormat(10000);
</script>

Or in a Node.js project:

const unitFormat = require('unitformat');

or

import unitFormat from 'unitformat';

The interface of UnitFormat.js is a single function that basically takes the number to be formatted and optionally the base unit, like "m" for meters:

let a = UnitFormat(1000, "m") // 1km
let b = UnitFormat(20000, "Hz") // 20kHz
let c = UnitFormat(1000) // 1k
let d = UnitFormat(0.02, "m") // 2cm

Available Parameters

The whole package consists of a single function UnitFormat with the following signature

UnitFormat(num, baseUnit="", prefixes="kMGTPE", base=10)

• num: the number to be formatted
• baseUnit: the base unit, like meters, Hertz, Joule, ...
• suffix: which suffixes should be used
• base: The number base, default is 10, but 2 is also possible for bytes

Suffixes

The suffix parameter is a string list of single-character metric prefixes, like kMGTPE. For base 10 the following prefixes can be used:

• E: Exa
• P: Peta
• T: Tera
• G: Giga
• M: Mega
• k: Kilo
• h: Hecto
• d: Deci
• c: Centi
• m: Milli
• u: Micro
• n: Nano
• p: Pico
• f: Femto
• a: Atto

And for base 2 the following prefixes are possible:

• k: Kilo
• M: Mega
• G: Giga
• T: Tera
• P: Peta
• E: Exa

Coding Style

As every library I publish, UnitFormat.js is also built to be as small as possible after compressing it with Google Closure Compiler in advanced mode. Thus the coding style orientates a little on maxing-out the compression rate. Please make sure you keep this style if you plan to extend the library.

Building the library

After cloning the Git repository run:

npm install
npm run build

Run a test

Testing the source against the shipped test suite is as easy as

npm run test

Copyright and Licensing

Copyright (c) 2025, Robert Eisele Licensed under the MIT license.