Simplify Fractions Calculator

Reduce proper, improper, and negative fractions to lowest terms and see the greatest common divisor used.

Reduce a fraction
Enter an integer numerator and a nonzero integer denominator.

About simplifying fractions

Simplifying a fraction means replacing it with an equivalent fraction whose numerator and denominator have no common factor greater than one. This final form is also called lowest terms or simplest form. The fraction keeps exactly the same value; only its representation changes. For example, 12 / 18 and 2 / 3 name the same point on a number line because both parts of 12 / 18 can be divided by 6. The calculator finds the greatest common divisor, often abbreviated GCD, of the numerator and denominator. It then divides both numbers by that divisor. Dividing the top and bottom by the same nonzero number preserves the ratio. Using the greatest common divisor completes the reduction in one step, although repeatedly dividing by smaller common factors eventually reaches the same answer. The Euclidean algorithm provides an efficient way to find the GCD. It repeatedly replaces a pair of integers with the smaller integer and the remainder after division. When the remainder becomes zero, the last nonzero divisor is the GCD. This approach works quickly even for large safe integers and avoids building a long list of every possible factor. Proper fractions have an absolute numerator smaller than the denominator, while improper fractions have an absolute numerator equal to or larger than the denominator. Both types simplify with the same process. When a reduced improper fraction has a remainder, the calculator also displays a mixed number. If it divides evenly, the fraction is shown as a whole number. A negative sign is normalized to the numerator so that the denominator remains positive, which is the conventional written form. Simplifying is useful before adding, subtracting, comparing, or communicating fractions. Smaller terms make patterns easier to recognize and often reduce arithmetic effort. A fraction with numerator zero always reduces to 0 / 1 because zero divided by any nonzero integer is zero. A denominator of zero is never accepted because division by zero is undefined. Enter integer values rather than decimals; if a measurement is decimal, convert it to a fraction first. The displayed reduction line shows the shared divisor so students can verify each division and understand why the simplified result is equivalent to the original.

Fraction simplification examples

Original fractionLowest termsMethod
12 / 182 / 3Divide both terms by the GCD 6.
42 / 127 / 2The mixed number is 3 1 / 2.
-24 / 36-2 / 3Divide both terms by the GCD 12.
15 / -25-3 / 5Normalize the negative sign to the numerator.

How to simplify a fraction

  1. Enter the integer above the fraction bar as the numerator.
  2. Enter a nonzero integer below the fraction bar as the denominator.
  3. Select Simplify Fraction to divide both terms by their greatest common divisor.
  4. Review the lowest-terms result, reduction work, and mixed or whole number when applicable.

Simplifying fractions FAQ

What does lowest terms mean?

A fraction is in lowest terms when its numerator and denominator share no factor greater than one. It cannot be reduced further while keeping integer terms.

Why divide both terms by the same number?

Dividing the numerator and denominator by the same nonzero number preserves their ratio. Therefore the simplified fraction remains equivalent to the original.

Can an improper fraction be simplified?

Yes, proper and improper fractions use the same GCD method. A reduced improper fraction can also be written as a mixed number or whole number.

How are negative fractions handled?

The calculator accepts a negative numerator or denominator and places the final sign on the numerator. A positive denominator keeps the result in conventional form.

Why is a zero denominator invalid?

A fraction bar represents division, and division by zero is undefined. Zero is allowed as the numerator and simplifies to 0 / 1.