How to use the Ratio Calculator
- Enter the known ratio as A and B.
- Enter the new value C and say whether it replaces A or B.
- Press Calculate to find the missing value.
Formula
If A : B = C : D, then A × D = B × C, so D = B × C ÷ A.
Examples
- Screen size: 16 : 9 at 1,920 px wide → 1,920 × 9 ÷ 16 = 1,080 px tall.
- Recipe: 2 cups flour for 3 eggs; with 5 eggs → 5 × 2 ÷ 3 = 3.33 cups.
Frequently asked questions
Is a ratio the same as a fraction?
A two-part ratio A : B can be written as the fraction A/B, but ratios can also have three or more parts, like 1 : 2 : 3 for a concrete mix.
How do I simplify a ratio?
Use the Ratio Simplifier, which divides all parts by their greatest common divisor.