Enter a numerator and denominator to reduce a fraction to its simplest form. The calculator gives the highest common factor used, so you can check each step in an exercise book rather than copying only the answer.
How to simplify a fraction
Find the highest common factor of the numerator and denominator, then divide both by that factor. This changes the way the fraction is written, not its value. A denominator of zero is not allowed because division by zero is undefined.
Worked example: 18 out of 24 learners
Suppose 18 of the 24 learners in a class walk to school. The fraction is 18/24. Both numbers are divisible by 6, and there is no larger common factor: 18 ÷ 6 = 3 and 24 ÷ 6 = 4. So 18/24 = 3/4. Check by multiplying 3/4 by 6/6 to get the original fraction.
For 12/8, the same method gives 3/2. That is a valid simplified improper fraction; it is also 1 1/2 as a mixed number. This tool leaves improper fractions in fraction form, so the common-factor step stays clear.
Input limits and privacy
Use whole numbers from -1 billion to 1 billion. Write a negative sign on either number; the result puts it on the numerator. Zero over a nonzero denominator simplifies to 0/1. Decimal inputs and zero denominators are rejected.
This is a free, independent learning aid for Kenyan families and teachers. It does not produce an examination grade or placement prediction. The calculator works on this device: it does not send or save the values you type.
Practise the method
Read our fractions revision guide, then try the Grade 6 Mathematics practice papers. You can also use the percentage change calculator or return to all free tools.
Method source
The mathematical rule is explained in OpenStax, Prealgebra 2e, section 4.2: Simplify Fractions, published by OpenStax at Rice University. The explanation and classroom example here are our own. Source checked 7 November 2026.
Frequently Asked Questions
What is the simplest form of 18/24?
It is 3/4. Divide both 18 and 24 by their highest common factor, 6.
Can I enter a negative or improper fraction?
Yes. Use whole-number inputs. Negative signs are kept in the numerator, and improper fractions remain in fraction form rather than changing to mixed numbers.
Why is a denominator of zero rejected?
A fraction represents division, and division by zero is undefined. Choose a nonzero denominator before calculating.
Are my inputs saved?
No. This calculator runs in your browser and does not send or store the numbers you enter.