Simplify a Ratio
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Solve a Proportion (A : B = C : D)
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Scale a Ratio by a Factor
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What This Tool Does
Three ratio tools in one: simplify any ratio to its lowest terms using GCD, solve a proportion when one of four values is unknown, and scale a ratio up or down by any factor. All results update live as you type.
Frequently Asked Questions
What is a ratio?
A ratio expresses the relative size of two or more values. The ratio 3:4 means "for every 3 of the first thing, there are 4 of the second." Ratios are used in recipes, maps, finance, image aspect ratios, and many other contexts.
What does simplifying a ratio mean?
Simplifying reduces a ratio to its smallest whole number form by dividing both values by their Greatest Common Divisor (GCD). For example, 8:12 simplifies to 2:3 because both are divisible by 4.
What is a proportion?
A proportion states that two ratios are equal: A:B = C:D. If one value is unknown, the proportion can be solved using cross-multiplication. For example, if 3:4 = X:12, then X = (3×12)/4 = 9.
Is my data sent to a server?
No. All calculations run in your browser. Nothing is transmitted anywhere.