Use a common denominator
a/b ± c/d = (ad ± bc)/(bd)
1/2 + 1/3 = 3/6 + 2/6 = 5/6.
5/6 − 1/3 = 5/6 − 2/6 = 1/2.
The common denominator makes the pieces the same size. This calculator uses the least common denominator before combining numerators.
Everyday math
Fraction Calculator
Calculate with two fractions and see the exact result, a decimal, and each step.
Calculate two fractions
Simplest exact result
Enter two fractions, then select Calculate.
Calculation steps
Your fraction inputs are processed in your browser.
How it works
Fraction formulas and examples
Multiply top and bottom
a/b × c/d = (a × c)/(b × d)
2/3 × 3/4 = 6/12 = 1/2.
For example, two-thirds of three-quarters of a cup is one-half cup. Reduce the result by dividing both numbers by their greatest common divisor.
Multiply by the reciprocal
a/b ÷ c/d = a/b × d/c
2/3 ÷ 4/5 = 2/3 × 5/4 = 10/12 = 5/6.
Turn the second fraction upside down, then multiply. The second fraction cannot be zero because division by zero is undefined.
Common questions
What does “simplest form” mean?
A fraction is in simplest form when its numerator and denominator have no common divisor greater than 1. For example, 18/24 becomes 3/4 after dividing both numbers by 6. A whole-number answer is shown as a whole number, and a zero answer is shown as 0.
Can I enter mixed numbers?
Convert a mixed number to an improper fraction first. For 1 1/2, multiply the whole part by the denominator and add the numerator: (1 × 2 + 1)/2 = 3/2. Enter 3 as the numerator and 2 as the denominator. For −1 1/2, enter -3 and 2.
How are negative fractions handled?
Put a keyboard minus sign (-) in the numerator and use a positive denominator. For example, for 2/−3 enter -2 as the numerator and 3 as the denominator. For a negative mixed result such as −1 1/6, the minus sign applies to the whole value: −(1 + 1/6).
Why is there an approximation sign next to the decimal?
The fraction answer is exact. Some decimals repeat forever, such as 1/3 = 0.333…; others need more places than selected. The decimal is rounded only for display, and ≈ appears when that displayed decimal differs from the exact fraction. Halfway values round away from zero. Changing decimal places does not change the exact fraction or the steps.
What are the input limits?
Each numerator and denominator can contain up to 15 digits, excluding an optional sign. Numerators may be positive, negative, or zero. Denominators must be greater than zero. Use integers without commas, decimal points, mixed-number notation, or exponents. Very long pasted text is rejected rather than silently shortened.