Ratio Calculator & Simplifier

Ratios turn up in recipes, screen dimensions, model scales, mixing paint, and every proportion question in school maths. This tool reduces a ratio to its simplest whole-number form and solves the classic "A is to B as C is to what" proportion for the missing term.

How to use it

1. Enter the two parts of your ratio to see it simplified.
2. Switch to proportion mode to solve for a missing term.
3. Fill in any three of the four values; the fourth is calculated for you.
4. Use the decimal equivalent to check scaling quickly.

Frequently asked questions

What is the difference between a ratio and a fraction?

A fraction compares a part with the whole; a ratio compares parts with each other. In a 2:3 mix there are five parts in total, so the first ingredient is 2/5 of the mixture, not 2/3.

How do I scale a recipe with this?

Use proportion mode. If the recipe serves 4 and you need 7, enter 4 : ingredient amount = 7 : unknown, and the tool returns the new quantity.

How do I find a screen aspect ratio?

Enter the pixel width and height and simplify. 1920 × 1080 reduces to 16:9, and 2560 × 1080 reduces to 64:27, the ultrawide format.

Can a ratio have decimals?

It can, but whole numbers are conventional. Multiply both terms by 10 or 100 until the decimals disappear, then simplify.

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