How to Subtract Fractions with the Same Denominator

When two fractions share the same denominator, you subtract the numerators and keep the denominator unchanged — no common denominator needed.

Step by step

1. 1
   Check the denominators match
   Both fractions need the same bottom number. For 5/8 and 2/8, both are 8.
2. 2
   Subtract the numerators
   Subtract the top numbers in order: 5 - 2 = 3.
3. 3
   Keep the denominator
   The denominator stays 8, giving 3/8.
4. 4
   Simplify if needed
   Reduce to lowest terms if possible. 3/8 is already lowest.

Worked example

Subtract 5/8 - 2/8. The denominators match, so subtract the numerators: 5 - 2 = 3. Keep the denominator 8. The answer is 3/8.

Common mistakes to avoid

• Subtracting the denominators too.
• Subtracting in the wrong order — order matters.
• Forgetting to simplify, e.g. 4/8 should become 1/2.

Practice this skill

Try it yourself on the Subtract Fractions Calculator, generate a printable worksheet, or work through it one step at a time in guided practice.