How do you simplify a ratio?

Divide both terms by their greatest common divisor. For example, 16 : 9 is already simplest, while 4 : 8 reduces to 1 : 2. The calculator does this automatically.

How do I solve a proportion like A : B = C : ?

Cross-multiply — the missing term equals B × C ÷ A. For example, 3 : 4 = 9 : ? gives 4 × 9 ÷ 3 = 12. Use the solve mode to compute it for you.

Is my data sent anywhere?

No. Everything is computed in your browser with plain arithmetic. Nothing you enter is uploaded or stored.

Ratio Calculator

Simplify ratios and solve proportions like A : B = C : ?

Ratio calculator

Simplify a ratio to its lowest terms (16 : 9, or 4 : 8 → 1 : 2), or solve a proportion for a missing term (3 : 4 = 9 : ? → 12).

Choose a mode, enter your numbers, and the answer updates instantly — entirely in your browser, nothing uploaded.