Ratio Calculator

Find the missing value in a proportion, reduce a ratio to its simplest whole numbers, or split an amount by any ratio.

Solve a proportion (A : B = C : x)

Finds x so that C relates to x the same way A relates to B.

x
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Simplify a ratio (A : B)

Simplest form
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As percentages
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With B as 1
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Split by ratio

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    What is a ratio calculator?

    Handle everyday ratio math in one place: scaling a recipe, reading a map scale, checking a screen's aspect ratio or splitting a shared bill. A proportion A : B = C : x is solved with x = B × C ÷ A, and a ratio is simplified by dividing by the greatest common divisor.

    How to use

    1. Pick the box for the calculation you need.
    2. Enter numbers. To split an amount, write the ratio with colons, like 3:2:1.
    3. The result appears right away.

    Frequently asked questions

    How do I solve a proportion?

    In A : B = C : x, the cross products are equal, so A × x = B × C and x = B × C ÷ A. For 3 : 4 = 15 : x, x is 20.

    Can ratios with decimals be simplified?

    Yes. A ratio like 1.5 : 2.5 is converted to whole numbers and reduced to 3 : 5.

    What if the split does not come out evenly?

    Shares are shown to four decimal places. When paying, round each share and add any leftover to one person.