Kulkalotar
Math & Conversion

Ratio Calculator (Simplify, Scale, Convert)

Simplify ratios, scale them to a target value, and convert ratios to decimals, percentages, and parts.

Simplified
2:3
As decimal
0.6667
A is
40.0%
B is
60.0%
B becomes:150.00

What this calculates

Ratios express the proportional relationship between two or more quantities. This calculator simplifies any ratio to its lowest terms, scales it when you know one side, and converts it to a decimal or percentage representation. Useful for recipe scaling, dilutions, mix design, aspect ratios, and financial proportions.

Formula & how it works

Simplify: divide both sides by GCD. 6:9 = 2:3 because GCD(6,9) = 3. Scale: if a:b and you know a' = new_a, then b' = b × (a'/a). Decimal: a:b = a/b. Percentage: a/(a+b) and b/(a+b). Aspect ratio decimal: width/height (16:9 = 1.778).

Worked example

Ratio 12:18. GCD(12,18) = 6. Simplified: 2:3. Decimal: 12/18 = 0.667. As percentages of total: 40 % and 60 %. Scale: if you need 100 of side A, then B = 18 × (100/12) = 150. 100:150 = 2:3 ✓.

Frequently asked questions

What's a 16:9 aspect ratio?

Width-to-height ratio for video and screens. Means 16 units wide for every 9 units tall (or 1.778:1). HD TVs and most YouTube videos are 16:9. Square is 1:1, classic film is 4:3, cinema widescreen is 2.39:1.

How do I make a 1:10 dilution?

1 part concentrate to 10 parts water — total 11 parts. For 110 mL final: 10 mL concentrate + 100 mL water. Mixing terminology varies; '1 in 10' sometimes means 1 part in 10 total (1+9).

Are ratios the same as fractions?

Related but expressed differently. 1:2 and 1/2 represent the same proportional relationship — half — but ratios emphasize comparison of parts while fractions emphasize a part of a whole.

How do I handle three-part ratios?

Same logic. To simplify a:b:c, find GCD of all three and divide. 6:12:18 = 1:2:3. To scale, ratio between any two sides defines the others.

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