A lightweight, high-precision big number utility for JavaScript and Node.js. Designed for financial calculations, blockchain integrations, and any environment where native JavaScript numbers are not enough.
- 🔢 Arbitrary-precision math using BigInt
- ⚡ Zero dependencies — fast & secure
- 🧮 Easy-to-use math functions (
add,sub,mul,div,pow, etc.) - 🧱 Type-safe and stable
- 🔒 Suitable for cryptography, blockchain, finance, token math
- 📦 Works in Node.js and bundlers (Vite, Webpack, etc.)
The library is the single JavaScript file big.js or the ES module big.mjs.
$ npm install bigmathutilsCommonJS:
const Big = require('bigmathutils');ES module:
import Big from 'bigmathutils';In the code examples below, semicolons and toString calls are not shown.
The library exports a single constructor function, Big.
A Big number is created from a primitive number, string, or other Big number.
x = new Big(123.4567)
y = Big('123456.7e-3') // 'new' is optional
z = new Big(x)
x.eq(y) && x.eq(z) && y.eq(z) // trueIn Big strict mode, creating a Big number from a primitive number is disallowed.
Big.strict = true
x = new Big(1) // TypeError: [bigmathutils] Invalid number
y = new Big('1.0000000000000001')
y.toNumber() // Error: [bigmathutils] Imprecise conversionA Big number is immutable in the sense that it is not changed by its methods.
0.3 - 0.1 // 0.19999999999999998
x = new Big(0.3)
x.minus(0.1) // "0.2"
x // "0.3"The methods that return a Big number can be chained.
x.div(y).plus(z).times(9).minus('1.234567801234567e+8').plus(976.54321).div('2598.11772')
x.sqrt().div(y).pow(3).gt(y.mod(z)) // trueLike JavaScript's Number type, there are toExponential, toFixed and toPrecision methods.
x = new Big(255.5)
x.toExponential(5) // "2.55500e+2"
x.toFixed(5) // "255.50000"
x.toPrecision(5) // "255.50"The arithmetic methods always return the exact result except div, sqrt and pow
(with negative exponent), as these methods involve division.
The maximum number of decimal places and the rounding mode used to round the results of these methods is determined by the value of the DP and RM properties of the Big number constructor.
Big.DP = 10
Big.RM = Big.roundHalfUp
x = new Big(2);
y = new Big(3);
z = x.div(y) // "0.6666666667"
z.sqrt() // "0.8164965809"
z.pow(-3) // "3.3749999995"
z.times(z) // "0.44444444448888888889"
z.times(z).round(10) // "0.4444444445"The value of a Big number is stored in a decimal floating point format in terms of a coefficient, exponent and sign.
x = new Big(-123.456);
x.c // [1,2,3,4,5,6] coefficient (i.e. significand)
x.e // 2 exponent
x.s // -1 signFor advanced usage, multiple Big number constructors can be created, each with an independent configuration.
To minify using, for example, npm and terser
$ npm install -g terser$ terser big.js -c -m -o big.min.jsThe test directory contains the test scripts for each Big number method.
The tests can be run with Node.js or a browser.
Run all the tests:
$ npm testTest a single method:
$ node test/toFixedFor the browser, see runner.html and test.html in the test/browser directory.
big-vs-number.html is a old application that enables some of the methods of bigmathutils to be compared with those of JavaScript's Number type.
The DefinitelyTyped project has a Typescript type definitions file for bigmathutils.
$ npm install --save-dev @types/bigmathutilsAny questions about the TypeScript type definitions file should be addressed to the DefinitelyTyped project.