Subtracting Fractions Calculator
Subtract one fraction from another with the common denominator, the subtraction and the simplification all written out step by step.
How to use it
- Type the numerator and denominator of each fraction.
- The answer is simplified automatically and shown as a decimal, a percentage and a mixed number.
- The working underneath is the same method you would use on paper.
Examples
| 3/4 − 1/2 | 1/4 |
| 1/3 − 3/4 | −5/12 |
Subtracting fractions follows the same common-denominator step as adding, then subtracts the numerators instead: a/b − c/d = (ad − cb) / bd.
Worked example — remaining material
A board is 3/4 of a metre long; 1/2 a metre is cut off. Remaining length: 3/4 − 1/2 = (3×2 − 1×4) / (4×2) = 2/8 = 1/4 metre after simplifying. The simplification step matters here — 2/8 and 1/4 are the same length, but 1/4 is what you'd actually mark on a tape measure.
Questions people ask
What if the answer comes out negative?
That is fine — it just means the second fraction was larger. The minus sign is kept on the numerator and the fraction is still simplified normally.
Is anything sent to a server?
No. Every calculation runs in your browser, so nothing you type is uploaded and the page keeps working offline once it has loaded.
Last updated 22 August 2026