➗ Ratio Calculator
Simplify a ratio, solve for a missing value in a proportion (A : B = C : ?), or split a total in a given ratio.
How the Ratio Calculator Works
A ratio compares quantities, such as 3 : 2. This calculator handles the three most common ratio tasks. Simplify reduces a ratio to its lowest whole-number terms by dividing by the greatest common factor; decimals are first scaled to whole numbers (1.5 : 2.5 becomes 3 : 5). Solve a proportion finds the missing value in A : B = C : ? using cross-multiplication, which is how recipes, maps, and scale drawings are resized.
Split a total divides an amount in a given ratio — for example sharing 1,200 in the ratio 1 : 2 : 3 gives 200, 400, and 600. You can use up to four parts.
Formula
Simplify: divide every term by their greatest common factor (GCF) Proportion: A : B = C : x → x = B × C ÷ A Split total: share(i) = total × part(i) ÷ sum of parts
How to Use It
- Choose what you want to do: simplify, solve, or split.
- Enter the ratio terms (and the known value or total where needed).
- Read the simplified ratio, the missing value, or each share.
- Use the decimal form (A ÷ B) when you need a single number.
Frequently Asked Questions
How do you simplify a ratio?
Divide all terms by their greatest common factor. For 12 : 18 the GCF is 6, so the ratio simplifies to 2 : 3. If there are decimals, multiply all terms by the same power of 10 first.
How do you solve a proportion?
Cross-multiply. In 4 : 6 = 10 : x, x = 6 × 10 ÷ 4 = 15.
How do you divide an amount in a ratio?
Add the parts of the ratio, divide the total by that sum to get the value of one part, then multiply by each part. 1,200 in the ratio 1 : 2 : 3 is 200, 400, and 600.
What is the difference between a ratio and a fraction?
A fraction compares a part with a whole; a ratio can compare any quantities, including part with part.
Related Glossary Terms
Related Calculators
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- 🔢 GCF & LCM Calculator — Greatest common factor and least common multiple, with prime factorizations.
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- 📊 Average Calculator (Mean, Median, Mode) — Get the mean, median, mode, range, and sum of any list of numbers.
Formula and content last reviewed: September 2026. All calculations run in your browser — nothing you enter is sent to or stored on our servers.
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See all →✔ Reviewed by GelirLab Editöryal Ekibi · Last reviewed: September 2026 · How we check our calculators