Ratio Calculator
Enter two numbers below to instantly simplify the ratio to its lowest terms.
Simplifying a Ratio
Find the greatest common factor (GCF) of both numbers, then divide each side of the ratio by it.
A common mistake is dividing by a shared factor that isn't the greatest one, then stopping too soon. Dividing 8:12 by 2 gives 4:6, which looks simplified but isn't — 4 and 6 still share a factor of 2, so it reduces further to 2:3. Always check that the two sides of the final ratio have no common factor left besides 1.
Worked example
Simplify 8:12.
GCF of 8 and 12 is 4.
8 ÷ 4 : 12 ÷ 4 = 2 : 3
A second example: simplify 18:24.
GCF of 18 and 24 is 6.
18 ÷ 6 : 24 ÷ 6 = 3 : 4
Keep going
- A ratio becomes a proportion once you set two of them equal; the proportion calculator solves for an unknown value in exactly that setup. Proportion Calculator
Frequently Asked Questions
How do you simplify a ratio?
Divide both numbers in the ratio by their greatest common factor (GCF). The result is the same ratio in its smallest whole-number form.
What does a ratio of 2:3 mean?
For every 2 units of the first quantity, there are 3 units of the second. It's a relative comparison, not an absolute amount.
Is a ratio the same as a fraction?
They're closely related — 2:3 can be written as the fraction 2/3 — but a ratio compares two separate quantities, while a fraction represents a part of a single whole.
What's the difference between a ratio and a rate?
A ratio compares two quantities measured in the same units, so the units cancel out (3 red marbles to 2 blue marbles is just 3:2). A rate compares two quantities in different units and keeps both, like 60 miles in 2 hours, which simplifies to a rate of 30 miles per hour rather than a unitless ratio.
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