Ratio Calculator

Simplify a ratio or find the missing term in a proportion a:b = c:d.

Reviewed & updated:

Solve A:B = C:D — enter A, B, C and D is computed.

Ratio A : B
A = 342.9%
B = 457.1%
D (solves A:B = C:D)4.5
Simplified A : B3 : 4

Results are estimates for general information only and are not professional financial, medical, tax, or legal advice. Read the full disclaimer.

How it works

Simplify by dividing both sides by GCD. Proportion: if a/b = c/d, then ad = bc.

Example

12:18 simplifies to 2:3. 2:3 = x:12 → x = 8.

Frequently asked questions

What is a ratio?
A comparison of two quantities by division.
Ratio vs fraction?
Same math; ratios express part-to-part, fractions part-to-whole.
How do I scale a recipe?
Multiply each ingredient by the same ratio.
Are 3:2 and 6:4 equal?
Yes — both simplify to 3:2.

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