Ratio Calculator

Instantly simplify ratios, find equivalent ratios, convert ratios to fractions or percentages, and solve for missing ratio values.

What Is a Ratio?

A ratio compares two quantities and expresses how many times one value contains another. Ratios can be written as A:B, A/B, or in words (A to B).

How to Simplify a Ratio

Divide both numbers by their greatest common divisor (GCD):

Example:
  20 : 30
  GCD(20, 30) = 10
  Simplified = 20÷10 : 30÷10 = 2 : 3

How to Solve Missing Ratio Terms

If you know A:B = C:D, you can solve for the unknown using:

A / B = C / D

Missing A → A = (B × C) / D  
Missing B → B = (A × D) / C  
Missing C → C = (A × D) / B  
Missing D → D = (B × C) / A

Convert Ratios to Percentages

The percentage form of A:B is:

Percentage = (A / (A + B)) × 100

Common Uses of Ratios

  • Mixing ingredients (cooking, chemistry)
  • Financial comparisons
  • Aspect ratios in design
  • Probability and statistics
  • Map scales and diagrams

Frequently Asked Questions

Yes, a ratio A:B is equivalent to the fraction A/B.
Yes. Example: 2:3:5 shows the relation among three quantities.
A ratio cannot have zero as both values. A:0 means undefined because division by zero is impossible.