Fraction Calculator
Add, subtract, multiply, or divide two fractions. The answer is reduced with the greatest common divisor, and division by zero is an error.
How to use
- Type the first fraction in Num 1 and Den 1. The sample is 1 over 2.
- Choose Op: + to add, − to subtract, × to multiply, or ÷ to divide. Type the second fraction in Num 2 and Den 2. The sample second fraction is 1 over 3.
- Press Calculate. The sample addition is 1/2 + 1/3, which reduces to 5 / 6. A decimal line under the fraction shows the same value, here about 0.833333.
- If you need a mixed number, read an improper result that way. 1/2 ÷ 1/3 is shown as 3 / 2, which is the mixed number 1 and 1/2, and the decimal line reads 1.5. The slash form is the reduced numerator and denominator after the greatest common divisor is divided out.
When it helps
Recipe halves, carpentry ratios, and school problems that must stay in fractions instead of a rounded decimal all fit. Multiplying 2/3 by 3/4 reduces to 1 / 2 rather than leaving 6 / 12 on the screen.
When the question is really "what percent is this," switch to the percentage calculator instead of dividing and then guessing. If you already know base and height, or three side lengths, the triangle calculator returns an area. This page only combines two fractions.
Limits
Divide by zero is an error. Op set to ÷ with Num 2 equal to 0 shows Division by zero. Den 1 or Den 2 equal to 0 shows Denominator cannot be 0. A blank denominator is treated as 1, and a blank numerator is treated as 0, so an empty box is not the same as typing 0 in a denominator.
Only two fractions are accepted, and every field is a whole number: 1.9 in Num 1 is truncated to 1. There is no separate whole-number box for mixed-number input, so convert 1 and 1/2 to 3 and 2 before you type.
Questions
How is the fraction reduced?
The greatest common divisor of the absolute values of the numerator and the denominator is divided out. A negative denominator is flipped so the sign sits on the numerator.
Will 7 divided by 3 show a mixed number?
7 / 3 is the reduced line. As a mixed number that is 2 and 1/3, and the decimal line shows the same quantity to at most six places. Use that reading when you need a whole part.
What if I divide by zero?
Calculate stops and reports an error. A zero second numerator under ÷ says Division by zero. A zero denominator says Denominator cannot be 0.