Simplify Fractions
Paste in a fraction and get it reduced to lowest terms, along with the greatest common factor that made it possible.
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The formula
Simplified fraction = (a / GCF) / (b / GCF), where GCF is the greatest common factor of a and b.
How to reduce a fraction
Find the biggest number that divides evenly into both the top and the bottom, then divide both by it. For 18/24 the biggest shared factor is 6, so 18/24 becomes 3/4.
If you cannot spot it, divide both numbers by any common factor and repeat until nothing else divides into both. You will get there, but the calculator uses the Euclidean algorithm to land on the answer in one go.
Quick divisibility checks
- Even numbers are divisible by 2.
- If the digits add up to a multiple of 3, the number is divisible by 3.
- Numbers ending in 0 or 5 are divisible by 5.
- If both numbers end in 0, you can cancel a 10 straight away.
Worked example
Simplify 126/84. The GCF of 126 and 84 is 42. 126 / 42 = 3 and 84 / 42 = 2, so the answer is 3/2, or 1 1/2.
Examples to check
Type these into the calculator above to see how it behaves. Every result below was produced by the same calculator code that runs on this page.
| What you enter | What you get |
|---|---|
| Fraction: 18/24 | Simplified fraction: 3/4 |
| Fraction: 126/84 | Simplified fraction: 3/2 |
| Fraction: 45/100 | Simplified fraction: 9/20 |
| Fraction: 7/13 | Simplified fraction: 7/13 |
Simplify Fractions: frequently asked questions
How do I know a fraction is fully simplified?
When the greatest common factor of the top and bottom is 1. The calculator shows the GCF so you can confirm it.
Can negative fractions be simplified?
Yes. The minus sign stays on the whole fraction, so -6/8 becomes -3/4.
Can I type mixed numbers?
Yes. Type a whole number, a space and then the fraction, for example 2 3/4. Decimals like 0.75 also work and are converted into fractions.
Does the calculator reduce the answer?
Always. The result is shown in its simplest form, as a mixed number and as a decimal, so you can use whichever your homework asks for.
How accurate is this calculator?
It uses standard double-precision arithmetic, accurate to about 15 significant digits. Results are rounded only for display.
Is what I enter in this calculator saved or sent anywhere?
No. The calculation runs in your browser, so what you enter is not sent to our servers. We only count, anonymously, whether a tool ran successfully.
Last reviewed: October 3, 2026