Ratio calculator (simplify and split)

Simplify a ratio A:B and, optionally, split a total in that proportion.

Simplified ratio

2 : 3

As decimal (A ÷ B)0.6667

Interactive lesson: The half nobody teaches 3 painters take 12 days. And 4 painters? If you answered 16, you fell for the inverse-proportion trap.

How the calculation works

A ratio compares two quantities (A:B, "A to B"). Two operations are the most common.

Simplifying a ratio

Divide both sides by the greatest common divisor (GCD), like a fraction: 20:30 = 2:3.

Splitting a total in an A:B proportion

Add the parts (A+B) and distribute:

part 1 = total × A/(A+B) · part 2 = total × B/(A+B)

Step-by-step example

Split R$500 in a 2:3 ratio:

Total parts: 2 + 3 = 5
Part 1: 500 × 2/5 = R$200
Part 2: 500 × 3/5 = R$300

Examples

Ratio 45:60 simplified: 3:4 (dividing by 15).
Mix 1:3 (cement:sand) for 8 kg: 2 kg cement and 6 kg sand.

Frequently asked questions

Ratio vs proportion?

A ratio compares A:B. A proportion is the equality of two ratios (A:B = C:D) — the basis of the rule of three.

Is a ratio the same as a fraction?

They are close: 2:3 equals the fraction 2/3. A ratio compares parts to each other; a fraction, a part of the whole.

How to split in three parts (A:B:C)?

Add A+B+C and multiply the total by each over that sum. E.g. 1:2:2 of 500 → 100, 200, 200.

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Updated on June 30, 2026 · by Rafael Rossi · Methodology & sources