Big Number Calculator

What is a big number calculator?

Ordinary calculators lose accuracy once numbers pass about 15–16 digits, rounding the rest away. A big number calculator works with arbitrary-precision integers, so every digit of the answer is exact — no matter how long. This version uses your browser's built-in BigInt support and never rounds.

What it can do

You can add, subtract, multiply and divide (getting both the quotient and remainder), take the modulo, raise a number to a power, find the greatest common divisor of two numbers, and compute a factorial. Results are shown in full, along with a count of how many digits they contain.

How to use this calculator

Type your first number, choose an operation, and enter the second number where required (the factorial uses only the first). Spaces and commas in your input are ignored, so you can paste grouped numbers. Press Calculate to see the exact result.

Where big numbers matter

Arbitrary-precision arithmetic is essential in cryptography, where keys are hundreds of digits long, as well as in combinatorics, number theory and scientific computing. Because these values overflow normal number types, a dedicated big number tool is the reliable way to keep every digit correct.