JavaScript Number.MIN_SAFE_INTEGER Property

Beginner
5 min read
Updated: Nov 2026
3 examples
Property
Decorative image with the word MINSAFEINTEGER

Definition

Number.MIN_SAFE_INTEGER is the smallest integer a JavaScript Number can represent exactly — -(253 - 1) (-9007199254740991). Below that, float rounding skips integers. It is a static property (ES2015), not a method.

Read the notes below before you rely on this property. Prefer feature detection when support is limited.

Syntax

Use Number.MIN_SAFE_INTEGER. Start with this line.

JavaScript
Number.MIN_SAFE_INTEGER
CallWhat it does
Number.MIN_SAFE_INTEGERPrimary signature.

Built into JavaScript. Read Number.MIN_SAFE_INTEGER on the Number constructor — no import required.

Library declarations
JavaScript
Number.MIN_SAFE_INTEGER

Parameters

ParameterDescription
BigIntOptional. Exact integers outside the safe range

Return Value

Return ValueDescription
*The current value of Number.MIN_SAFE_INTEGER.

JavaScript Examples

Example 1 — Read Number.MIN_SAFE_INTEGER

Print the constant and confirm it equals -Number.MAX_SAFE_INTEGER.

JavaScript
console.log(Number.MIN_SAFE_INTEGER);
console.log(Number.MIN_SAFE_INTEGER === -(2 ** 53 - 1));
console.log(Number.MIN_SAFE_INTEGER === -Number.MAX_SAFE_INTEGER);
Try It Yourself

How It Works

  1. Static access. Read Number.MIN_SAFE_INTEGER on the constructor.
  2. Exact value. Engines print -9007199254740991.
  3. Definition. That number is exactly -(2 ** 53 - 1).
  4. Mirror of max. It equals -Number.MAX_SAFE_INTEGER — same safe window, lower bound.

Example 2 — Precision Loss Past the Limit

Subtracting 1 or 2 below the min safe integer produces the same float.

JavaScript
const min = Number.MIN_SAFE_INTEGER;

console.log(min - 1);
console.log(min - 2);
console.log(min - 1 === min - 2);  // true — not safe!
Try It Yourself

How It Works

  1. At the edge. min is still exact.
  2. Next even float. min - 1 lands on -9007199254740992.
  3. Odd skipped. min - 2 cannot store a distinct odd integer — same bits.
  4. Dangerous equality. === says they match even though the math differs.

Example 3 — Guard with Number.isSafeInteger

Check values at the lower boundary before trusting integer math.

JavaScript
const min = Number.MIN_SAFE_INTEGER;

console.log(Number.isSafeInteger(min));      // true
console.log(Number.isSafeInteger(min - 1));  // false
console.log(Number.isSafeInteger(-9007199254740991)); // true
Try It Yourself

How It Works

  1. At the limit. min itself is a safe integer → true.
  2. One below. min - 1 is outside the safe range → false.
  3. Literal form. The decimal literal -9007199254740991 is the same safe value.
  4. Use as a gate. Reject or convert to BigInt when the check fails.
Compatibility

Browser & Runtime Support

Number.MIN_SAFE_INTEGER is part of ES2015 and is Baseline Widely available in modern browsers and Node.js.

✓ Baseline · ES2015

Number.MIN_SAFE_INTEGER

Supported in Chrome, Firefox, Safari, Edge, and Node.js for years. Safe for modern apps without a polyfill.

98% Modern browser support
Google Chrome Supported · Desktop & Mobile
Full support
Mozilla Firefox Supported · Desktop & Mobile
Full support
Apple Safari Supported · macOS & iOS
Full support
Microsoft Edge Supported · Chromium
Full support
Internet Explorer No native support · Use a polyfill
Polyfill
Opera Supported · Modern versions
Full support
Samsung Internet Supported · Android
Full support
Bun Supported · JavaScript runtime
Supported
Deno Supported · JavaScript runtime
Supported
Node.js Supported · Server runtime
Supported
Android WebView Supported · Modern WebView
Full support
Number.MIN_SAFE_INTEGER Excellent

Bottom line: Use Number.MIN_SAFE_INTEGER freely in modern JavaScript. Older engines without it can use the literal -(Math.pow(2, 53) - 1) as a fallback.

Frequently Asked Questions

Number.MIN_SAFE_INTEGER is the smallest integer JavaScript can represent exactly as a Number — -(2^53 - 1), which is -9007199254740991. Below that, consecutive integers are no longer all representable.
Yes. Read it on Number itself: Number.MIN_SAFE_INTEGER. There is no (5).MIN_SAFE_INTEGER on number instances, and it is not a method.
MIN_SAFE_INTEGER equals -MAX_SAFE_INTEGER. Together they bound the safe integer window: from -(2^53 - 1) to 2^53 - 1.
Safe means integers can be represented exactly and compared correctly. Past the bound, Number.MIN_SAFE_INTEGER - 1 === Number.MIN_SAFE_INTEGER - 2 is true — which is mathematically wrong.
No. MIN_VALUE (~5e-324) is the smallest positive Number near zero. MIN_SAFE_INTEGER is the most negative exact integer (~-9e15).
It is Baseline Widely available (ES2015) and supported in every modern browser and Node.js.

Next: POSITIVE_INFINITY

Learn how JavaScript represents values beyond the finite Number range.

POSITIVE_INFINITY tutorial →

About the author

Mari Selvan M P
Mari Selvan M P 🔗

Developer, cloud engineer, and technical writer

  • Experience 12 years building web and cloud systems
  • Focus Full Stack Development, AWS, and Developer Education

I write practical tutorials so students and working developers can learn by doing—from databases and APIs to deployment on AWS.

AWS Certified Developer – Associate (Credly)

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JavaScript Number.MAX_SAFE_INTEGER Property JavaScript Number.POSITIVE_INFINITY Property