Ratio Calculator
Solve proportions and simplify ratios
A : B = C : D
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Leave one field empty to solve for it
How Ratios Work
A ratio compares two quantities. If A:B = C:D, then:
A × D = B × C
This is called "cross multiplication" and is used to solve for unknown values in proportions.
Common Ratio Uses
- Recipes: Scale ingredients up or down
- Maps: 1:100,000 means 1 inch = 100,000 inches
- Finance: Price-to-earnings ratios
- Mixing: Paint, concrete, cocktails
- Photography: Aspect ratios (16:9, 4:3)