Web/JavaScript/Reference/Global objects/Number/MAX SAFE INTEGER

The Number.MAX_SAFE_INTEGER constant represents the maximum safe integer in JavaScript (253 - 1).

For larger integers, consider using BigInt.

Property attributes of `Number.MAX_SAFE_INTEGER`
Writable	no
Enumerable	no
Configurable	no

Description

The MAX_SAFE_INTEGER constant has a value of 9007199254740991 (9,007,199,254,740,991 or ~9 quadrillion). The reasoning behind that number is that JavaScript uses double-precision floating-point format numbers as specified in IEEE 754 and can only safely represent integers between -(253 - 1) and 253 - 1.

Safe in this context refers to the ability to represent integers exactly and to correctly compare them. For example, Number.MAX_SAFE_INTEGER + 1 === Number.MAX_SAFE_INTEGER + 2 will evaluate to true, which is mathematically incorrect. See Number.isSafeInteger() for more information.

This field does not exist in old browsers. Using it without checking its existence, such as Math.max(Number.MAX_SAFE_INTEGER, 2), will yield undesired results such as NaN.

Because MAX_SAFE_INTEGER is a static property of Number, you always use it as Number.MAX_SAFE_INTEGER, rather than as a property of a Number object you created.

Polyfill

if (!Number.MAX_SAFE_INTEGER) {
    Number.MAX_SAFE_INTEGER = 9007199254740991; // Math.pow(2, 53) - 1;
}

Examples

Return value of MAX_SAFE_INTEGER

Number.MAX_SAFE_INTEGER; // 9007199254740991

Numbers higher than safe integer

This returns 2 because in floating points, the value is actually the decimal trailing "1" except for in subnormal precision cases such as zero.

Number.MAX_SAFE_INTEGER * Number.EPSILON; // 2

Specifications

Specification
ECMAScript (ECMA-262)The definition of 'Number.MAX_SAFE_INTEGER' in that specification.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
`MAX_SAFE_INTEGER`	Chrome Full support 34	Edge Full support 12	Firefox Full support 31	IE No support No	Opera Full support 21	Safari Full support 9	WebView Android Full support ≤37	Chrome Android Full support 34	Firefox Android Full support 31	Opera Android Full support 21	Safari iOS Full support 9	Samsung Internet Android Full support 2.0	nodejs Full support 0.12

Legend

Full support: Full support
No support: No support