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Owais Khan Software Reviews

Ratio Calculator and Proportion Calculator

Simplify a ratio, solve a proportion, and split an amount by a ratio.

Calculate ratios and proportions

Simplify a ratio

2 : 3

40% / 60%

Equivalent: 4:6, 6:9, 8:12

Solve a proportion a / b = c / d

Leave one box empty.

d = 12

Split an amount by a ratio

40.00 + 60.00

Everything stays on this device — what you enter never leaves your browser.

Ratio calculator

This ratio calculator simplifies a ratio to lowest terms, shows it as percentages and lists equivalent ratios. 12:18 simplifies to 2:3, which is 40% and 60%. You can enter two or more terms, with decimals.

Proportion calculator

The proportion calculator solves a / b = c / d for the one value you leave blank, by cross-multiplying: 3 / 4 = 9 / d gives d = 12. To simplify a ratio first, use the box on the left.

Split an amount by a ratio

To share 100 in the ratio 2:3 you get 40.00 and 60.00. The parts are rounded to the cent and always add up to the amount, which matters for splitting costs, profits or ingredients. For percentages of a whole, the final grade calculator and GPA calculator use the same idea.

Frequently asked questions

How do I simplify a ratio?
Divide every term by their greatest common divisor. For 12:18, the greatest common divisor of 12 and 18 is 6, so 12:18 simplifies to 2:3. Ratios with decimals are scaled to whole numbers first, so 0.5:2.5 becomes 1:5. Type a ratio above and the simplest form is shown, along with the percentage split 40% and 60%.
How do I solve a proportion?
A proportion says two ratios are equal, a / b = c / d. To find a missing value, cross-multiply: a × d = b × c, then divide by the term opposite the unknown. For 3 / 4 = 9 / d, d = (4 × 9) ÷ 3 = 12. Leave one of the four boxes empty in the proportion calculator and the missing value is filled in.
How do I find equivalent ratios?
Multiply or divide every term of a ratio by the same number. 2:3 is equivalent to 4:6, 6:9 and 8:12, because each is the original multiplied by 2, 3 or 4. All equivalent ratios simplify to the same lowest terms, which is how you check whether two ratios are the same.
How do I divide an amount by a ratio?
Add the terms to get the number of equal parts, divide the amount by it, then multiply by each term. To share 100 in the ratio 2:3: 2 + 3 = 5 parts of 20, giving 40.00 and 60.00. When the amount does not divide evenly, the calculator rounds to the cent and hands out the leftover cents so the parts still add up to the total.
How do I convert a ratio to a percentage?
Divide each term by the sum of all the terms and multiply by 100. For 2:3 the total is 5, so the shares are 2 / 5 = 40% and 3 / 5 = 60%. For a three-part ratio such as 1:2:2 the shares are 20%, 40% and 40%. The simplify tool shows the percentages for any ratio you enter.
Is my data uploaded or processed on a server?
No. The calculations run inside this page, so what you enter never leaves your browser, and there is no sign-up. That is enforced rather than promised: this site’s test suite scans the shipped HTML for every browser API capable of sending data off the page and fails the build if it finds one.