Ratio Calculator

Simplify ratios like 12:18 to 2:3, find the missing term in A:B = C:D, or divide a total in a ratio.

What Do You Want to Find?
Fractions and decimals both work.
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Ratio
Simplest form
As 1 : n
As a fraction and percent
Work

Saved Calculations

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How to Work With Ratios

A ratio compares two amounts. It keeps its meaning when both terms are multiplied or divided by the same number, which is how you simplify or scale it.

Simplify: divide A and B by their greatest common factor
Scale: A : B = C : D  →  D = B × C ÷ A
Split a total T: A’s share = T × A ÷ (A + B)

Worked Example

Tips

Decimal ratios are simplified by first multiplying both terms by 10, 100, … to make them whole: 1.5 : 2.5 becomes 15 : 25, then 3 : 5.