ToolBirch

GCD & LCM Calculator

Greatest common divisor and least common multiple.Math & Statistics

GCD & LCM Calculator

Greatest common divisor and least common multiple of two positive integers, via the Euclidean algorithm.

About this tool

The Euclidean algorithm gives the GCD exactly, and LCM follows as A times B over GCD. The building blocks of fraction simplification and cycle scheduling.

How to use the GCD & LCM Calculator tool

  1. Enter two positive integers. Whole numbers only.
  2. Read both results. GCD and LCM together.
  3. Use them. Fraction reduction, gear ratios, event scheduling.

Supported formats

Input

  • Plain text or file input

Output

  • Converted or analysed output

Inputs are validated before anything is processed. Invalid values and unsupported files are rejected with a clear error instead of failing silently.

Frequently asked questions

How fast is it?

The Euclidean algorithm is logarithmic in the smaller number — instant at any practical size.

Why must both be positive?

GCD and LCM are defined for positive integers in this tool.

What about more than two numbers?

Two at a time; chain the tool for more.

Privacy

Everything you enter stays in this browser tab. There is no upload endpoint for tool inputs, no account, and no server-side copy of your text or files. Results are produced locally and disappear when you close the page.

No account is required and no file is ever uploaded. See the privacy policy for details about analytics and the limited data this site stores.

Known limitations

  • Two inputs only; no multi-number mode.

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