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Ratio Calculator

By Lucas Meyer · Last updated 15 October 2026

18:24 looks clumsy. 3:4 says the same thing, with smaller numbers. That is all simplifying a ratio does: divide every part by the biggest number that divides them all exactly. Here that number is 6, so 18:24 becomes 3:4, and the calculator below simplifies any ratio and splits an amount into shares by ratio.

Enter your numbers

Leave blank for a two-part ratio.

Result

Splitting $500 Without Arguing

A ratio compares two or more quantities of the same kind. 3:2 means for every 3 parts of one thing there are 2 parts of another. A proportion is a statement that two ratios are equal, such as 3:2 = 6:4.

Split $500 by 3:2. Total parts = 3 + 2 = 5. Each part = $500 ÷ 5 = $100. The shares are 3 × $100 = $300 and 2 × $100 = $200. Check: $300 + $200 = $500. In general, with ratio a:b and total T, total parts = a + b, each part = T ÷ (a + b), and the shares are a × each part and b × each part.

Enter the ratio parts in the First part, Second part, and Third part (optional) fields, and the amount to split in the Amount to split field. The calculator returns the simplified ratio and each share, with the working shown.

Simplifying: Smaller Numbers, Same Split

To simplify, divide every part by the GCD, the largest number that divides all parts exactly. For 18 and 24: divisors of 18 are 1, 2, 3, 6, 9, 18. Divisors of 24 are 1, 2, 3, 4, 6, 8, 12, 24. The largest shared divisor is 6. Divide both parts by 6: 18 ÷ 6 = 3, 24 ÷ 6 = 4. Simplified ratio = 3:4.

A simplified ratio keeps the same relationship with smaller numbers. 18:24 and 3:4 describe the same split. When splitting money, shares always add back up to the total. If they do not, something went wrong. Ratios only compare like with like, so do not mix units. Convert first (the Unit Converter does that) and then compare. Ratio parts must be positive numbers. Zero and negative parts have no meaning in a split, and the calculator will flag them.

Ratios as Fractions and Percents

A ratio also reads as a fraction of the total. With a:b, the first part is a ÷ (a + b) of the total, and its percentage is a ÷ (a + b) × 100. Split $500 by 3:2 and the shares are 3/5 and 2/5 of the total, or 60% and 40%.

Two places this shows up constantly. A recipe scaled 2:3:5 takes 20%, 30%, and 50% of the total. A map at 1:50,000 means 1 cm on the map stands for 50,000 cm (0.5 km) on the ground.

Things People Wonder

How do I simplify a ratio?

Divide every part by the GCD, the largest number that divides all parts exactly. For 18:24 the GCD is 6, so 18:24 simplifies to 3:4.

How do I split money by ratio?

Add the parts to get the total number of parts, divide the total by that number to get the value of one part, then multiply by each part. Splitting $500 by 3:2 gives parts of $100, so the shares are $300 and $200.

What is the difference between ratio and proportion?

A ratio compares quantities, like 3:2. A proportion says two ratios are equal, like 3:2 = 6:4. You solve proportion problems by cross-multiplying: if 3/2 = x/8, then x = 12.

Can a ratio have three parts?

Yes. Recipes and mixes often use three-part ratios, like 2:3:5 for flour, sugar, and butter. Simplify them the same way: divide all three parts by their shared GCD, and split totals by adding all three parts first.

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