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Free online fraction calculator to quickly add, subtract, multiply, and divide fractions. Easily simplify fractions and convert mixed numbers.
Enter integers for numerator and denominator (numerator can be negative). Select an operation to calculate and simplify automatically. (Tip: Numerator is the top number, denominator is the bottom number.)
Overview
Understand what the tool solves, how it works, and the boundaries of its data.
Enter the numerator and denominator for each of two fractions, then choose addition, subtraction, multiplication, or division. Inputs are whole integers, including negative values. The result is reduced to lowest terms and shown as a fraction (or whole integer) with its decimal value.
A fraction a/b represents a numerator divided by a nonzero denominator. For addition and subtraction, cross-multiply to create a common denominator: a/b ± c/d = (ad ± bc)/bd. Multiplication multiplies top by top and bottom by bottom. Division multiplies the first fraction by the reciprocal of the second. The calculator then divides numerator and denominator by their greatest common divisor and places a negative sign on the numerator.
For example, 1/2 + 1/3 = (1×3 + 1×2)/(2×3) = 5/6, which is approximately 0.8333. The fraction remains exact even when its decimal representation repeats. A decimal shown for a repeating fraction is a numeric display, so use the reduced fraction when exactness matters.
Guide
Follow the workflow and verify inputs and outputs with practical examples.
Type an integer numerator and a nonzero integer denominator in each fraction. Use a negative sign in either part if needed; the result is normalized with the sign on top.
Select plus, minus, multiplication, or division. The result updates from the entered values.
Use the simplified fraction for an exact answer and the decimal for an approximate numerical view. For a whole-number result, the fraction display omits a denominator.
To check an addition example, 3/4 + 2/5 = (15+8)/20 = 23/20 = 1.15. If the result is negative, the sign stays with the numerator; if it reduces to an integer, the denominator is no longer needed.
Use cases
See how the tool fits into real work and everyday tasks.
A learner can compare an operation’s reduced fraction with handwritten work, then use the decimal to make a quick magnitude check.
A cook scaling a recipe can add or multiply fractional quantities, keeping the fraction result exact before converting it to a practical measure.
An editor or analyst can verify a two-fraction calculation without first converting both values to rounded decimals.
Q&A
Find concise answers to common questions and confusing cases.
No. Enter one integer numerator and denominator for each fraction. Convert the mixed number first: 2 1/3 is 7/3.
A fraction’s denominator must be nonzero. Replace any zero denominator with a valid nonzero integer before calculating.
That would divide by zero, which is undefined. Choose a nonzero second fraction or a different operation.
Some fractions have repeating decimal expansions. The reduced fraction is the exact result; the decimal is provided as a convenient numeric representation.
Notes
Review scope, result limitations, and important precautions before use.
The calculator uses integer numerator and denominator fields and a decimal numeric display. Very large integers can exceed the exact integer range of ordinary browser number arithmetic; for unusually large values, verify the result with arbitrary-precision arithmetic. For ordinary classroom-sized fractions, retain the simplified fraction when a rounded decimal would lose needed precision.
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