Ratio Calculator
Simplify ratios, solve proportions, and scale mixtures — with decimal and percentage forms
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Quick summary
Three modes: simplify a ratio to lowest terms (16:24 → 2:3), solve a proportion for the missing value (16:24 = 4:? → 6), or scale a ratio by any factor (2:3 doubled → 4:6). Every result also shows the decimal ratio and each side's percentage share — handy for mixtures, recipes, screens, and maps.
Reviewed by Simple Calculators TeamLast reviewed
How to use this calculator
- Enter the inputs requested by the calculator.
- Choose the units or options that match your situation and review the assumptions.
- Run or update the calculation to see the result.
- Review the result, breakdown, and formulas shown on the page.
- Check the inputs, units, dates, and limitations before saving or sharing the result.
Frequently asked questions
How do I simplify a ratio?
Divide both sides by their greatest common divisor: 16:24 has a GCD of 8, giving 2:3. The simplified ratio expresses the same relationship with the smallest whole numbers.
How do I solve a proportion?
Cross-multiply: if A:B = C:D and D is unknown, D = B×C ÷ A. For 16:24 = 4:D, D = 24×4 ÷ 16 = 6. This is the workhorse for recipe scaling, map distances, and unit pricing.
What is the difference between a ratio and a fraction?
A ratio compares parts to parts (2:3 sand to cement); a fraction compares a part to the whole (2/5 of the mix is sand). The calculator shows both views — the percentage shares are the part-to-whole reading.
How do aspect ratios work?
Screens and images use width:height ratios — 16:9 for most displays, 4:3 for older ones. A 2560×1440 monitor simplifies to 16:9; the solve mode finds matching dimensions at any size.
Key terms
- Proportion
- An equation of two equal ratios (A:B = C:D) — solvable by cross-multiplication.
- Lowest Terms
- A ratio whose sides share no common factor — the simplest equivalent form.
- Part-to-Part vs Part-to-Whole
- 2:3 is part-to-part; the same data as part-to-whole is 40% and 60%.
Methodology, sources & limitations
This page shows the formula, assumptions, and limitations used for this estimate. Rates, thresholds, and other time-sensitive inputs can change, so verify them against the relevant official source before relying on a result.
For our review approach and the primary sources we consult, see the methodology and source policy. If you spot an outdated figure or formula, please contact us with a correction.