Simplify Fractions Calculator
Enter a fraction (or a mixed number) to reduce it to lowest terms. You get the greatest common divisor with every Euclidean algorithm step, the mixed number, the exact decimal with its repeating digits, and a list of equivalent fractions.
For a mixed number like 2 3/4, enter 2 here
Decimals such as 2.5/10 are allowed
How to use the Simplify Fractions Calculator
- Enter the numerator and denominator of your fraction.
- Add a whole number if you have a mixed number such as 2 3/4 (optional).
- Press Simplify (results also update as you type).
- Read the simplified fraction, mixed number, decimal and percent.
- Check the steps and the Euclidean algorithm table, or copy the results.
How fraction simplification works
A fraction a/b is reduced to lowest terms by dividing both parts by their greatest common divisor:
a/b = (a ÷ GCD(a, b)) / (b ÷ GCD(a, b))
The GCD comes from the Euclidean algorithm, which relies on the fact that GCD(a, b) = GCD(b, a mod b). For 120/84: 120 = 84 × 1 + 36, 84 = 36 × 2 + 12, 36 = 12 × 3 + 0, so GCD = 12 and 120/84 = 10/7 = 1 3/7. This is much faster than listing every factor, even for very large numbers.
A simplified fraction converts to a terminating decimal only when its denominator has no prime factors other than 2 and 5 (1/8 = 0.125). Any other denominator gives a repeating decimal (1/6 = 0.1(6), 1/7 = 0.(142857)).
Common fractions in simplest form
| Fraction | GCD | Simplest form | Decimal | Percent |
|---|---|---|---|---|
| 2/4 | 2 | 1/2 | 0.5 | 50% |
| 6/9 | 3 | 2/3 | 0.(6) | 66.67% |
| 8/12 | 4 | 2/3 | 0.(6) | 66.67% |
| 15/20 | 5 | 3/4 | 0.75 | 75% |
| 12/16 | 4 | 3/4 | 0.75 | 75% |
| 10/25 | 5 | 2/5 | 0.4 | 40% |
| 14/21 | 7 | 2/3 | 0.(6) | 66.67% |
| 18/24 | 6 | 3/4 | 0.75 | 75% |
| 24/36 | 12 | 2/3 | 0.(6) | 66.67% |
| 45/60 | 15 | 3/4 | 0.75 | 75% |
| 35/56 | 7 | 5/8 | 0.625 | 62.5% |
| 120/84 | 12 | 10/7 = 1 3/7 | 1.(428571) | 142.86% |
Tips
- If both numbers are even, you can always divide by 2 first; if the digit sums are both multiples of 3, divide by 3.
- Two different prime numbers (like 17/23) or two consecutive integers (like 8/9) are always already in lowest terms.
- To add or compare fractions, use a common denominator first, then simplify the answer at the end.
Frequently asked questions
How do you simplify a fraction?
Find the greatest common divisor (GCD) of the numerator and the denominator, then divide both by it. For 24/36 the GCD is 12, so 24/36 = (24 ÷ 12)/(36 ÷ 12) = 2/3.
What does lowest terms mean?
A fraction is in lowest terms (simplest form) when the numerator and denominator have no common factor other than 1, that is, when their GCD is 1. For example 2/3 and 17/23 are in lowest terms, but 6/9 is not.
How is the GCD found?
The calculator uses the Euclidean algorithm: divide the larger number by the smaller, replace the pair with the smaller number and the remainder, and repeat until the remainder is 0. The last non-zero remainder is the GCD.
How do I simplify a mixed number?
Convert it to an improper fraction first (whole × denominator + numerator, over the denominator), simplify that, then turn it back into a mixed number. 2 6/8 becomes 22/8, which simplifies to 11/4 = 2 3/4.
Can I simplify a fraction with decimals?
Yes. Multiply the top and bottom by a power of 10 to make them whole numbers, then simplify. 2.5/10 becomes 25/100, which reduces to 1/4.
Does simplifying change the value of a fraction?
No. Dividing the numerator and denominator by the same number gives an equivalent fraction with exactly the same value, just written with smaller numbers.
Where does the minus sign go in a negative fraction?
−3/4, 3/−4 and −(3/4) are all equal. By convention the simplified answer puts the minus sign on the numerator and keeps the denominator positive.