Fraction Calculator
Working with fractions by hand means finding common denominators, flipping divisors, and reducing the answer — small steps that are easy to slip on. This fraction calculator adds, subtracts, multiplies, and divides two fractions and always returns the result in lowest terms, alongside its decimal value. It is the tool for halving a recipe, combining measurements in inches and sixteenths, or checking homework, where the exact fraction matters more than a rounded decimal.
Calculate
Default result: 5
Fraction Calculator · Result
calculators.dev
Result numerator
add × 1 × 2 × 1 × 3
- Result denominator
- 6
- As a decimal
- 0.8333
Reviewed by the calculators.dev team · Last updated 2026-06-23
How to calculate
Pick the operation, then type the numerator and denominator of each fraction. For addition and subtraction the calculator rewrites both fractions over a common denominator before combining them; for multiplication it multiplies the tops and bottoms straight across; for division it multiplies by the reciprocal of the second fraction. Whatever the operation, the answer is reduced by cancelling the greatest common divisor of the top and bottom, so 6/12 is shown as 1/2. The result updates the moment you change a value.
Add or subtract: a/b ± c/d = (a·d ± c·b) / (b·d). Multiply: a/b × c/d = (a·c) / (b·d). Divide: a/b ÷ c/d = (a·d) / (b·c). Every result is then reduced by dividing the numerator and denominator by their greatest common divisor, and the sign is carried on top so the denominator stays positive.
Example calculation
Adding 1/2 and 1/3 means giving them a common denominator of 6: 1/2 becomes 3/6 and 1/3 becomes 2/6. Three sixths plus two sixths is 5/6, which is already in lowest terms because 5 and 6 share no common factor. The decimal equivalent is about 0.8333.
- numerator
- 5
- denominator
- 6
- decimal
- 0.8333
Assumptions
- Numerators and denominators are whole numbers; mixed numbers must be converted to improper fractions first (2 1/3 becomes 7/3).
- Neither denominator may be zero, and division by a fraction whose numerator is zero is rejected, because both mean dividing by nothing.
- The answer is always given in lowest terms; a negative result keeps its sign on the numerator.
Common mistakes
- Adding numerators and denominators straight across (1/2 + 1/3 ≠ 2/5) — addition needs a common denominator first.
- Forgetting to flip the second fraction when dividing; a/b ÷ c/d multiplies by d/c, not c/d.
- Leaving the answer unreduced, so 8/12 is reported instead of the simpler 2/3.
Frequently asked questions
How do I add two fractions with different denominators?
Rewrite each fraction over the common denominator, then add the numerators. 1/2 + 1/3 becomes 3/6 + 2/6 = 5/6.
How do I divide one fraction by another?
Multiply the first fraction by the reciprocal of the second. 1/2 ÷ 1/4 = 1/2 × 4/1 = 4/2 = 2.
Does the calculator simplify the answer?
Yes. Every result is reduced to lowest terms by cancelling the greatest common divisor of the numerator and denominator.
Can I enter a mixed number like 2 1/3?
Convert it to an improper fraction first: 2 1/3 is (2 × 3 + 1)/3 = 7/3. Enter 7 as the numerator and 3 as the denominator.