GCD Calculator

Find the Greatest Common Divisor (also called HCF) of two or more numbers.

GCD (HCF)

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How to use the GCD Calculator

Type two or more whole numbers separated by commas.
Click Calculate.
Read the GCD (also called HCF or GCF).
Use the LCM calculator if you need the lowest common multiple instead.

Euclidean algorithm

GCD(a, b) = GCD(b, a mod b), repeated until the remainder is 0

Worked example

GCD of 48 and 180

180 = 3 × 48 + 36

48 = 1 × 36 + 12

36 = 3 × 12 + 0

GCD = 12

Uses of GCD

GCD is used to simplify fractions (48/180 ÷ 12 = 4/15), to split items into equal groups without leftovers, and to find the largest square tile that fits a rectangular floor exactly. For example, the largest square tile for a 480 cm × 1,800 cm area without cutting is 120 cm, because GCD(480, 1800) = 120.

Tips for accurate results

GCD of any number and 0 is the number itself.
If GCD is 1, the numbers are called co-prime.
GCD(a, b) × LCM(a, b) = a × b for two numbers.

Frequently Asked Questions

Yes. GCD (greatest common divisor), HCF (highest common factor) and GCF mean the same thing.

Find GCD of the first two, then the GCD of that result with the third.

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Content reviewed by Vinod, Easy Smart Calculator · Last updated October 2026