Reference formulas and worked examples below keep their stated units. Monetary examples use USD; dimensional examples use US customary units unless labeled otherwise. Metric calculator inputs are converted to these reference units before calculation. Choosing another currency does not convert example amounts or exchange money.
How to use this fraction calculator
Enter two numbers and choose an operation. Examples: 3/4, 1 1/2, -2/3, or 0.25.
How the calculation works
For a/b + c/d, the numerator is ad + bc and denominator is bd. Subtraction replaces + with −.
Multiplication gives ac/bd. Division gives ad/bc, provided the second number is not zero.
The numerator and denominator are divided by their greatest common divisor. Integer arithmetic preserves the exact fraction; the decimal is an approximation rounded to at most eight decimal places.
Worked example
3/4 + 1/6 = (3 × 6 + 1 × 4) / (4 × 6) = 22/24 = 11/12. The decimal approximation is 0.91666667.
Limits and assumptions
Supports up to 12 digits per fraction component, or 12 total digits and 9 decimal places for decimal input. A denominator cannot be zero. Negative denominators should be entered with the sign on the numerator.
Frequently asked questions
Can I enter mixed numbers?
Yes. Separate the whole number and fraction with a space, such as 2 3/4.
How do I simplify one fraction?
Enter it as the first number and add 0 as the second number.
Is the decimal answer exact?
The simplified fraction is exact. Some decimals repeat forever, so the displayed decimal is a rounded approximation.