How do you simplify a ratio?

Divide every term by their greatest common divisor. For 12:18 the greatest common divisor is 6, so the ratio simplifies to 2:3. If a term has decimals, first multiply all terms by the same power of ten to make them whole: 1.5:4.5 becomes 15:45, which simplifies to 1:3.

How do I split an amount in a ratio?

Add the terms, divide the total by that sum, then multiply by each term. To split 120 in the ratio 2:3:5, the terms add up to 10, so one part is 12 and the shares are 24, 36 and 60.

What does a 1 : n ratio mean?

It's the same ratio rescaled so the first term is 1, which makes ratios easy to compare. 4:6 is 1 : 1.5 and 3:12 is 1 : 4. The second number can be a decimal; that's expected in this form.

Can a ratio have more than two terms?

Yes. A recipe or a mix often has three or more parts, like 2:3:5. Simplifying, splitting and scaling all work the same way for up to 10 terms.

How is this different from the aspect ratio and rule of three calculators?

The Aspect Ratio Calculator is built for screen and image sizes in width × height. The Rule of Three Calculator solves one missing value in A/B = C/X. This tool is for general ratios: simplifying them, splitting amounts and scaling all terms at once.

RATIO CALCULATOR

Simplify, split and scale ratios with any number of terms. Nothing leaves your browser.

In short

Enter a ratio like 4:6 or 2:3:5 to get it in lowest terms (2:3), as 1 : n (1 : 1.5) and as percentage shares of the whole. You can also split a total in that ratio or scale it so one term hits a value you choose. Everything is calculated in your browser.

Ratio

Two or more numbers separated by colons, e.g. 4:6, 1.5:4.5 or 2:3:5.

Simplified2 : 3

As 1 : n1 : 1.5

Shares of the whole40% · 60%

Split a total in this ratio

Part 1 (4)40
Part 2 (6)60

Scale the ratio

Termbecomes

Scaled10 : 15

How to use the ratio calculator

1
Type a ratio with its terms separated by colons, such as 4:6, 1.5:4.5 or 2:3:5.
2
Read the simplified ratio, the 1 : n form and each term's share of the whole.
3
To divide an amount, enter the total under "Split a total" and read each part.
4
To scale the ratio, pick a term and the value it should become, and read the scaled ratio.

Questions

How do you simplify a ratio?: Divide every term by their greatest common divisor. For 12:18 the greatest common divisor is 6, so the ratio simplifies to 2:3. If a term has decimals, first multiply all terms by the same power of ten to make them whole: 1.5:4.5 becomes 15:45, which simplifies to 1:3.
How do I split an amount in a ratio?: Add the terms, divide the total by that sum, then multiply by each term. To split 120 in the ratio 2:3:5, the terms add up to 10, so one part is 12 and the shares are 24, 36 and 60.
What does a 1 : n ratio mean?: It's the same ratio rescaled so the first term is 1, which makes ratios easy to compare. 4:6 is 1 : 1.5 and 3:12 is 1 : 4. The second number can be a decimal; that's expected in this form.
Can a ratio have more than two terms?: Yes. A recipe or a mix often has three or more parts, like 2:3:5. Simplifying, splitting and scaling all work the same way for up to 10 terms.
How is this different from the aspect ratio and rule of three calculators?: The Aspect Ratio Calculator is built for screen and image sizes in width × height. The Rule of Three Calculator solves one missing value in A/B = C/X. This tool is for general ratios: simplifying them, splitting amounts and scaling all terms at once.

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Updated October 19, 2026