Ratio Calculator
Solve ratios and proportions
Solve A : B = C : D
Leave one field blank — it will be solved.
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Missing value =
Simplify a ratio
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About the Ratio Calculator
This ratio calculator solves proportions and simplifies ratios. To find a missing value, enter any three of the four numbers in the proportion A:B = C:D and the calculator finds the fourth. To simplify a ratio, enter both values and get the reduced form.
Common uses include scaling recipes up or down, mixing paints or solutions to a specific ratio, resizing images while maintaining aspect ratio, and solving proportion problems in maths. Works with any numerical values, including decimals.
Frequently asked questions
How do I scale a recipe with this?
Enter the original ratio (e.g. 2 cups flour : 1 cup sugar = 2 : 1) and one new value. The calculator solves for the missing number while keeping the proportion intact.
What if my ratio doesn't simplify cleanly?
Ratios with no common factor stay as-is. The calculator returns the simplest equivalent form, but a ratio like 7 : 11 already is in simplest form and won't reduce further.