logo

Proportion Calculator — Free Online (Tolyo.app)

Solve for missing values in proportions (a/b = c/d). Fast • Private • Client-side.

Proportion Calculator
Trending

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.
Category
Calculators
Badge
Trending
Privacy
Client-side

Example

If 3/4 = x/8, thenx = (3 × 8) / 4 = 6.

Given
a=3, b=4, d=8
Find
c = x
Result
x = 6

You might also find these tools useful

Handy companions for working with Text, QR Code and Images.