How to use this calculator
Enter each fraction’s numerator and denominator, then choose an operation. Simplify uses only the first fraction. Use whole-number components; put a minus sign on either component for a negative fraction.
The math behind it
a/b + c/d = (ad + bc)/bd a/b − c/d = (ad − bc)/bd a/b × c/d = ac/bd a/b ÷ c/d = ad/bc Reduce numerator and denominator by their greatest common divisor.
A worked example
1/3 + 1/6 = 3/6 = 1/2, or 0.5. Dividing 2/3 by 4/5 gives 10/12 = 5/6.
Assumptions & precision
Components are signed integers of at most 15 digits, including leading zeros. Decimal components, exponent notation and mixed-number notation are not supported. Denominators cannot be zero; the fraction you divide by cannot equal zero. Native BigInt arithmetic preserves the exact fraction even when intermediate products exceed safe JavaScript number precision. A negative denominator is moved to the numerator. The decimal approximation uses Number arithmetic and displays up to 6 decimal places, with scientific notation for tiny values.
A common question
Why does a fraction sometimes have a rounded decimal?
Fractions such as 1/3 have repeating decimal expansions. The simplified fraction is exact; the decimal display is an approximation.