A JavaScript library for arbitrary-precision decimal and non-decimal arithmetic.
[](https://www.npmjs.com/package/bignumber.js)
[](https://www.npmjs.com/package/bignumber.js)
[](https://github.com/MikeMcl/bignumber.js/actions/workflows/ci.yml)
- [Features](#features)
- [Build](#build)
- [Load](#load)
- [Use](#use)
- [Test](#test)
- [Minify](#minify)
- [Licence](#licence)
## Features
- Integers and decimals
- Simple API but full-featured
- Faster, smaller, and perhaps easier to use than JavaScript versions of Java's BigDecimal
- 8 KB minified and gzipped
- Replicates the `toExponential`, `toFixed`, `toPrecision` and `toString` methods of JavaScript's Number type
- Includes a `toFraction` and a correctly-rounded `squareRoot` method
- Supports cryptographically-secure pseudo-random number generation
- No dependencies
- Wide platform compatibility: uses JavaScript 1.5 (ECMAScript 3) features only
- Comprehensive [documentation](http://mikemcl.github.io/bignumber.js/) and test set
If a smaller and simpler library is required see [big.js](https://github.com/MikeMcl/big.js/).
It's less than half the size but only works with decimal numbers and only has half the methods.
It also has fewer configuration options than this library, and does not allow `NaN` or `Infinity`.
See also [decimal.js](https://github.com/MikeMcl/decimal.js/), which among other things adds support for non-integer powers, and performs all operations to a specified number of significant digits.
## Build
*bignumber.js* is the single source file, and *bignumber.d.ts* contains the type declarations for it. The build script, *build.js*, creates targeted builds in a *dist* directory for ES module, CommonJS, and browser usage.
To run the build script (requires Node.js ≥ 14.14.0):
```bash
npm install
npm run build
# or: node build.js
```
A *dist* directory will be created containing the following:
| Module format | Distributable | Type declaration |
| --- | --- | --- |
| ES module (ESM) | bignumber.mjs | bignumber.d.mts |
| CommonJS (CJS) | bignumber.cjs | bignumber.d.cts |
| Browser (global) | bignumber.js | bignumber.d.ts |
## Load
### Browser
```html
```
or, minified from a CDN (Content Delivery Network):
```html
```
> ES module
```html
```
or, minified from a CDN:
```html
```
### [Node.js](http://nodejs.org)
```bash
npm install bignumber.js
```
> CommonJS
```javascript
const BigNumber = require('bignumber.js');
// or, testing from a local repo:
const BigNumber = require('./dist/bignumber.cjs');
```
> ES module
```javascript
import BigNumber from 'bignumber.js';
// or
import { BigNumber } from 'bignumber.js';
// or, testing from a local repo:
import { BigNumber } from './dist/bignumber.mjs';
```
### [Deno](https://deno.land/)
```javascript
// @deno-types="https://raw.githubusercontent.com/MikeMcl/bignumber.js/main/dist/bignumber.d.mts"
import BigNumber from 'https://raw.githubusercontent.com/MikeMcl/bignumber.js/main/dist/bignumber.mjs';
// or
// @deno-types="https://unpkg.com/bignumber.js@latest/dist/bignumber.d.mts"
import { BigNumber } from 'https://unpkg.com/bignumber.js@latest/dist/bignumber.mjs';
```
## Use
The library exports a single constructor function, [`BigNumber`](http://mikemcl.github.io/bignumber.js/#bignumber), which accepts a value of type Number, String, BigInt or BigNumber,
```javascript
let x = new BigNumber(123.4567);
let y = BigNumber('123456.7e-3');
let z = new BigNumber(x);
x.isEqualTo(y) && y.isEqualTo(z) && x.isEqualTo(z); // true
```
To get the string value of a BigNumber use [`toString()`](http://mikemcl.github.io/bignumber.js/#toS) or [`toFixed()`](http://mikemcl.github.io/bignumber.js/#toFix). Using `toFixed()` prevents exponential notation being returned, no matter how large or small the value.
```javascript
let x = new BigNumber('1_234_567_890_000_000_000_000');
x.toString(); // "1.23456789e+21"
x.toFixed(); // "1234567890000000000000"
```
If the limited precision of Number values is not well understood, it is recommended to create BigNumbers from String values rather than Number values to avoid a potential loss of precision.
*In all further examples below, `let`, semicolons and `toString` calls are not shown. If a commented-out value is in quotes it means `toString` has been called on the preceding expression.*
```javascript
// Precision loss from using numeric literals with more than 15 significant digits.
new BigNumber(1.0000000000000001) // '1'
new BigNumber(88259496234518.57) // '88259496234518.56'
new BigNumber(99999999999999999999) // '100000000000000000000'
// Precision loss from using numeric literals outside the range of Number values.
new BigNumber(2e+308) // 'Infinity'
new BigNumber(1e-324) // '0'
// Precision loss from the unexpected result of arithmetic with Number values.
new BigNumber(0.7 + 0.1) // '0.7999999999999999'
```
When creating a BigNumber from a Number, note that a BigNumber is created from a Number's decimal `toString()` value not from its underlying binary value. If the latter is required, then pass the Number's `toString(2)` value and specify base 2.
```javascript
new BigNumber(Number.MAX_VALUE.toString(2), 2)
```
BigNumbers can be created from string values in bases from 2 to 36. See [`ALPHABET`](http://mikemcl.github.io/bignumber.js/#alphabet) to extend this range.
```javascript
a = new BigNumber('1011', 2) // "11"
b = new BigNumber('zz.9', 36) // "1295.25"
c = a.plus(b) // "1306.25"
```
*Explicitly passing base 10 is not recommended as it will cause the slower base conversion path to be used, which is only necessary if an unconventional `ALPHABET` has been specified.*
A BigNumber is immutable in the sense that it is not changed by its methods.
```javascript
0.3 - 0.1 // 0.19999999999999998
x = new BigNumber(0.3)
x.minus(0.1) // "0.2"
x // "0.3"
```
The methods that return a BigNumber can be chained.
```javascript
x.dividedBy(y).plus(z).times(9)
x.times('1.23456780123456789e+9').plus(9876.5432321).dividedBy('4444562598.111772').integerValue()
```
Some of the longer method names have a shorter alias.
```javascript
x.squareRoot().dividedBy(y).exponentiatedBy(3).isEqualTo(x.sqrt().div(y).pow(3)) // true
x.modulo(y).multipliedBy(z).eq(x.mod(y).times(z)) // true
```
As with JavaScript's Number type, there are [`toExponential`](http://mikemcl.github.io/bignumber.js/#toE), [`toFixed`](http://mikemcl.github.io/bignumber.js/#toFix) and [`toPrecision`](http://mikemcl.github.io/bignumber.js/#toP) methods.
```javascript
x = new BigNumber(255.5)
x.toExponential(5) // "2.55500e+2"
x.toFixed(5) // "255.50000"
x.toPrecision(5) // "255.50"
x.toNumber() // 255.5
```
A base can be specified for [`toString`](http://mikemcl.github.io/bignumber.js/#toS).
```javascript
x.toString(16) // "ff.8"
```
*Again, explicitly passing base 10 is not recommended as it will cause the slower base conversion path to be used, which is only necessary if an unconventional `ALPHABET` has been specified.*
There is a [`toFormat`](http://mikemcl.github.io/bignumber.js/#toFor) method which may be useful for internationalisation.
```javascript
y = new BigNumber('1234567.898765')
y.toFormat({
prefix: '€',
decimalSeparator: ',',
groupSeparator: '.',
decimalPlaces: [0, 2]
}) // "€1.234.567,90"
```
The maximum number of decimal places of the result of an operation involving division (i.e. a division, square root, base conversion or negative power operation) is set using the `set` or `config` method of the `BigNumber` constructor.
The other arithmetic operations always give the exact result.
```javascript
BigNumber.set({ DECIMAL_PLACES: 10, ROUNDING_MODE: 4 })
x = new BigNumber(2)
y = new BigNumber(3)
z = x.dividedBy(y) // "0.6666666667"
z.squareRoot() // "0.8164965809"
z.exponentiatedBy(-3) // "3.3749999995"
z.toString(2) // "0.1010101011"
z.multipliedBy(z) // "0.44444444448888888889"
z.multipliedBy(z).decimalPlaces(10) // "0.4444444445"
```
There is a [`toFraction`](http://mikemcl.github.io/bignumber.js/#toFr) method with an optional *maximum denominator* argument
```javascript
y = new BigNumber(355)
pi = y.dividedBy(113) // "3.1415929204"
pi.toFraction() // [ "7853982301", "2500000000" ]
pi.toFraction(1000) // [ "355", "113" ]
```
and [`isNaN`](http://mikemcl.github.io/bignumber.js/#isNaN) and [`isFinite`](http://mikemcl.github.io/bignumber.js/#isF) methods, as `NaN` and `Infinity` are valid `BigNumber` values.
```javascript
x = new BigNumber(NaN) // "NaN"
y = new BigNumber(Infinity) // "Infinity"
x.isNaN() && !y.isNaN() && !x.isFinite() && !y.isFinite() // true
BigNumber.set({ STRICT: false })
z = new BigNumber('zzz')
z.isNaN() // true
```
The value of a BigNumber is stored in a decimal floating point format in terms of a coefficient, exponent and sign.
```javascript
x = new BigNumber(-123.456);
x.c // [ 123, 45600000000000 ] coefficient (i.e. significand)
x.e // 2 exponent
x.s // -1 sign
```
For advanced usage, multiple BigNumber constructors can be created, each with its own independent configuration.
```javascript
// Set DECIMAL_PLACES for the original BigNumber constructor
BigNumber.set({ DECIMAL_PLACES: 10 })
// Create another BigNumber constructor, optionally passing in a configuration object
BN = BigNumber.clone({ DECIMAL_PLACES: 5 })
x = new BigNumber(1)
y = new BN(1)
x.div(3) // '0.3333333333'
y.div(3) // '0.33333'
```
To avoid having to call `toString` or `valueOf` on a BigNumber to get its value in the Node.js REPL or when using `console.log` use
```javascript
BigNumber.prototype[require('util').inspect.custom] = BigNumber.prototype.valueOf;
```
For further information see the [API](http://mikemcl.github.io/bignumber.js/) reference in the *doc* directory.
## Test
The *test/methods* directory contains the test scripts for each method.
The tests can be run with Node.js or a browser. The tests require the CommonJS distributable, so **build before testing**:
```bash
npm run build
npm test
# or: node test/test
```
To test a single method, use, for example
```bash
node test/methods/toFraction
```
For the browser, open *test/test.html*.
There are also some old programs in *perf* that still work and can be useful for testing and cross-checking results over large sets of random inputs.
### TypeScript
The *test/typescript* directory contains TypeScript compilation tests that verify the type declarations and imports work correctly for each module format. Run them with:
```bash
npm run typecheck
```
## Minify
To minify using, for example, [terser](https://github.com/terser/terser):
```bash
npm install -g terser
```
Minify the browser/global bundle:
```bash
terser dist/bignumber.js -c -m -o dist/bignumber.min.js
```
## Licence
The MIT Licence.
See [LICENCE](https://github.com/MikeMcl/bignumber.js/blob/main/LICENCE.md).