Math

Ratio Calculator

Simplify ratios, find missing values, and scale ratios up or down.

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Ratio Calculator

Mode

Value A

Value B

Scale Factor

Results

Formula & Methodology

Simplification: Divide both values by their GCD
Example: 8:12 → GCD(8,12)=4 → 2:3

Proportion: a:b = c:d → d = (b×c)/a

About Ratio Calculator

A ratio compares two or more quantities. Our ratio calculator helps you simplify ratios to their lowest terms, solve proportions, and scale ratios for recipes, maps, and models.

Frequently Asked Questions

A ratio compares two or more quantities of the same kind. It shows how many times one value contains or is contained within another. Ratios can be written as a:b, a/b, or "a to b".

Find the GCD of all numbers in the ratio and divide each by it. For example, the ratio 12:8 simplifies to 3:2 (dividing both by 4). Our calculator simplifies ratios automatically.

Divide the target total by the sum of ratio parts, then multiply each part by that factor. For example, to split $300 in a 2:1 ratio: factor = 300/3 = 100. Shares are $200 and $100.

A proportion states that two ratios are equal: a/b = c/d. This is used to solve for an unknown value. If 3/4 = x/20, then x = (3 × 20) / 4 = 15.

Ratios are fundamental in cooking for scaling recipes. If a recipe for 4 serves uses a 3:1 flour-to-water ratio, scaling to 8 servings keeps the same ratio but doubles the quantities.

A fraction represents a part of a whole (part/total), while a ratio compares two separate quantities (part:part). For example, if a class has 3 boys and 5 girls, the boy-to-girl ratio is 3:5, but boys are 3/8 of the class.

Use cross-multiplication. If a:b = c:x, then a×x = b×c, so x = (b×c)/a. For example, if 2:5 = 8:x, then x = (5×8)/2 = 20.

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