Ratio Calculator
Simplify a ratio between two numbers to its lowest terms.
Try an example
2 : 3
About this calculator
How This Ratio Calculator Works
Enter two numbers, and the calculator simplifies them to the smallest whole-number ratio that represents the same proportion, plus the decimal equivalent.
Worked Example
8:12 simplifies to 2:3 — both numbers divided by their greatest common factor, 4.
The Formula
A ratio is simplified by dividing both numbers by their greatest common factor (GCF). Since 8 and 12 share a GCF of 4, dividing both by 4 gives 2:3 — a ratio that represents the exact same proportion, just in its smallest whole-number form. The GCF Calculator shows this step on its own.
Worked example
8:12 shares a greatest common factor of 4 — divide both sides by 4 and the ratio simplifies to 2:3, equivalent to 8 ÷ 12 = 0.666667.
Frequently asked questions
How do you simplify a ratio?
Divide both numbers by their greatest common factor (GCF). For 8:12, the GCF is 4, so 8÷4 : 12÷4 gives 2:3.
What if the two numbers share no common factor?
Then the ratio is already in its simplest form — for example, 5:9 can't be reduced further since their GCF is 1.
What's the difference between a ratio and a fraction?
A ratio (2:3) compares two separate quantities, while a fraction (2/3) usually represents a part of a single whole — but the simplification math works the same way for both.
Can a ratio have more than two numbers?
Yes — ratios like 2:3:5 compare three or more quantities at once. This calculator handles two-number ratios; simplify a multi-part ratio by dividing every term by their shared GCF.