Add Fractions Calculator

About this calculator

Adding two fractions with different denominators requires first rewriting both over a common denominator, typically the least common denominator (LCD), the smallest number both original denominators divide into evenly, before the numerators can simply be added together; the result is then reduced to lowest terms by dividing both numerator and denominator by their greatest common divisor.

This process is one of the foundational skills in elementary and middle-school arithmetic, and it underlies practical tasks like combining measurements in recipes, adding 1/3 cup and 1/4 cup for example, adding fractional lengths in carpentry and construction measured in inches, and computing combined probabilities or proportions expressed as fractions in early statistics.

Enter two fractions and this calculator adds them and returns the result in fully simplified lowest terms.