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

Like all my libraries, UnitFormat.js is written to minimize size after compression with Google Closure Compiler in advanced mode. The code style is optimized to maximize compressibility. If you extend the library, please preserve this style.

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.