Proportion Calculator — Free Online (Tolyo.app)
Solve for missing values in proportions (a/b = c/d). Fast • Private • Client-side.
How the Proportion Calculator Works
This Tolyo.app free online tool uses cross multiplication to solve equations of the forma/b = c/d. Enter any three values and leave the unknown blank.
Cross-multiplication formulas
- a = (b × c) / d
- b = (a × d) / c
- c = (a × d) / b
- d = (b × c) / a
Why Tolyo.app?
Free Online- Client-side only — your inputs never leave your device.
- Mobile-first design with accessible controls.
- No login, completely free online.
Example
If 3/4 = x/8, thenx = (3 × 8) / 4 = 6.
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