Fraction Simplifier
Reduce any fraction or mixed number to its lowest terms. Enter the numerator and denominator — plus a whole part in mixed-fraction mode — and the calculator divides both by their greatest common factor and shows the whole hand calculation: the gcf line, the cancelling step, the simplified fraction, the mixed form when one exists, and the decimal and percent. Everything runs locally in your browser with integer arithmetic.
Pick a mode and enter the fraction
Simple Fraction mode takes just a numerator over a denominator, like 2/4 or -1/2. Switch to Mixed Fraction mode to add a whole part, like 1 1/2 or -2 1/3 (the minus in front of the whole number makes the value negative). Only integers are accepted, and the denominator cannot be 0.
Press Calculate
The tool converts a mixed number to an improper fraction (whole × denominator + numerator), finds the greatest common factor of the numerator and denominator with the Euclidean algorithm, and divides both by it. A negative denominator just flips the sign: 1/-2 simplifies to -1/2.
Read the result and the steps
You get the simplified fraction, the mixed form when the value is greater than 1 without being a whole number, and the decimal and percent. The Calculation box spells it out, e.g. 2/4 gives gcf(2,4) = 2, then (2/2)/(4/2) = 1/2, then 0.5 = 50%. Press Reset to clear the fields.
How to simplify a fraction
- The rule: divide top and bottom by the same number
- A fraction is in lowest terms when the numerator and denominator share no common factor other than 1. Dividing both by their greatest common factor (gcf) gets you there in one move: 4/6 has gcf(4,6) = 2, so 4/6 = (4÷2)/(6÷2) = 2/3. The Calculation box shows exactly this cancelling step.
- Improper fractions and mixed numbers
- When the numerator is larger than the denominator the fraction is improper: 1 1/2 first becomes (1×2 + 1)/2 = 3/2, and after reducing it is written back as a mixed number — here 3/2 = 1 1/2 — whenever a remainder is left over. A result that divides evenly (4/2) is shown as 2/1 and 2, with no mixed row.
- Negative fractions
- The sign applies to the whole value, never to the denominator. Enter -1/2, 1/-2, or -2 1/3 (minus in front of the whole part) and the sign rides on the result: -1/2, -1/2, and -7/3 = -2 1/3. Zero keeps no sign: 0/5 simplifies to 0/1 with decimal 0 and percent 0%.
- Decimal and percent
- Each result also shows its decimal and percent form, rounded to 5 decimal places with trailing zeros trimmed (1/3 → 0.33333 → 33.33333%). These display choices are this calculator's own convention.
- What inputs does the calculator reject?
- A missing numerator or denominator (in either mode); anything that is not a plain integer — decimals like 2.5, scientific notation like 1e3, signs like +3 or bare letters; a denominator of 0; and numbers beyond JavaScript's exact-integer range (about 9 quadrillion). Invalid input shows an in-app error and clears the previous result.
More fraction tools and other math utilities live in the Math & Statistics category.
Privacy: every simplification runs in your browser tab — no value you type is sent anywhere, and nothing is stored after you close the page.