How do you simplify a fraction?

Find the greatest common divisor (GCD) of the numerator and denominator. Divide both by the GCD. The result is the fraction in its simplest form (lowest terms). If the GCD is 1, the fraction is already fully simplified.

What is the greatest common divisor?

The GCD (also called HCF, highest common factor) is the largest number that divides both the numerator and denominator without a remainder. For 12 and 8, the GCD is 4, so 12/8 simplifies to 3/2.

What does it mean for a fraction to be in its simplest form?

A fraction is in simplest form (or lowest terms) when the numerator and denominator share no common factors other than 1. That is, their GCD is 1. For example, 3/4 is already in simplest form, but 6/8 is not (it simplifies to 3/4).

Can it simplify a negative fraction?

Negative numerators and denominators both work, and the sign moves to the numerator, so 6/-8 simplifies to -3/4.

Simplify fractions calculator

Reduce any fraction to its simplest form. Enter the numerator and denominator and this calculator finds the greatest common divisor (GCD) and divides both parts by it to give the fully simplified fraction. The step-by-step working shows you the method. All calculations run locally in your browser.

How it works

To simplify 18/24, the calculator finds the greatest common divisor with Euclid's algorithm (24 mod 18 = 6, then 18 mod 6 = 0, so the GCD is 6) and divides both parts by it to give 3/4. When the GCD is 1, the working says the fraction is already in its simplest form. All arithmetic runs in JavaScript in your browser.

Processing runs in your browser

All calculations happen locally in your browser tab. Our servers are not involved at any point.

Related operations

For converting a fraction into a percentage, try the percentage calculator. To switch between metric and imperial measures, use the unit converter. For translating numbers into Roman numerals, see the Roman numeral converter.

Frequently asked questions

How do you simplify a fraction?: Find the greatest common divisor (GCD) of the numerator and denominator. Divide both by the GCD. The result is the fraction in its simplest form (lowest terms). If the GCD is 1, the fraction is already fully simplified.
What is the greatest common divisor?: The GCD (also called HCF, highest common factor) is the largest number that divides both the numerator and denominator without a remainder. For 12 and 8, the GCD is 4, so 12/8 simplifies to 3/2.
What does it mean for a fraction to be in its simplest form?: A fraction is in simplest form (or lowest terms) when the numerator and denominator share no common factors other than 1. That is, their GCD is 1. For example, 3/4 is already in simplest form, but 6/8 is not (it simplifies to 3/4).
Can it simplify a negative fraction?: Negative numerators and denominators both work, and the sign moves to the numerator, so 6/-8 simplifies to -3/4.

Last reviewed September 30, 2026

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