Ratio Calculator
Simplify a ratio to lowest terms, or solve a proportion for the missing term.
Reviewed by the OmniCalc teamMethod verified 2026-07-01
3 : 4
= = 0.75 as a decimal
3 : 4Show steps
- Divide both terms by their greatest common factor.
- 18 : 24 = 3 : 4.
- As a decimal, 18 ÷ 24 = 0.75.
How to use the ratio calculator
- 1Pick Simplify to reduce a : b, or Solve to fill in a : b = c : ?.
- 2Enter your numbers — whole numbers for simplifying, any values for solving.
- 3Read the result and open Show steps for the working.
Ratios are just fractions
The ratio 3 : 4 is the fraction 3/4 in disguise, which is why the same greatest-common-factor trick simplifies both. Scaling a recipe or mixing paint is exactly this: keep the fraction, change the numbers.
Frequently asked questions
How do you simplify a ratio?
Divide both terms by their greatest common factor. For 18 : 24 the GCF is 6, giving 3 : 4 — the same relationship in the smallest whole numbers.
How do I solve a proportion?
For a : b = c : x, cross-multiply to get a·x = b·c, then divide: x = (b × c) ÷ a. Enter three of the four terms and the calculator returns the fourth.
Can I simplify decimals?
Simplifying to whole-number terms expects whole numbers. If you have decimals, scale both sides first (for example ×10) so they become integers, or use the proportion mode, which accepts decimals.