Fraction Calculator

Cross multiplication: a/b + c/d = (a·d + c·b) ÷ (b·d). Same denominator for both terms, then sum the numerators. The result is automatically simplified to lowest terms.

Multiplication is the easy one: a/b × c/d = (a·c) ÷ (b·d). For division, flip the second fraction and multiply: a/b ÷ c/d = (a·d) ÷ (b·c). "Invert the divisor" is the same rule.

Because fractions are equivalence classes. 2/4, 3/6 and 4/8 are all the same number; the simplest form (here 1/2) is the canonical representative. The calculator divides numerator and denominator by their GCD to land in lowest terms.

Convert first: 1 1/2 = 3/2 (multiply the whole part by the denominator and add the numerator). The calculator works with improper fractions; if you need a mixed-number output, divide the result with remainder by hand: 5/6 stays 5/6, but 7/6 = 1 1/6.

Yes. Use a negative numerator (e.g. −1/2). The sign is carried on the numerator and the denominator is normalized to positive. "Negative denominator" inputs are accepted and converted to the equivalent positive-denominator form internally.