Ratio Calculator

Simplify a ratio to its lowest terms, or scale a ratio to find a missing value.

▼ Enter a ratio to simplify it to lowest terms
:
Simplified Ratio
▼ Enter a known ratio and one value to find the missing value
: = :
Missing Value

Simplifying and Solving Ratios

This tool simplifies ratios to their lowest terms and solves for a missing value in a proportion (e.g. "12 is to 18 as 3 is to what?") — common in recipe scaling, map scales, and ratio-based word problems.

Example: the ratio 12:18 simplifies to 2:3 — and if you know 3:5 equals 12:?, this tool solves for the missing value directly.

Simplifying Ratios

A ratio is simplified by dividing both terms by their greatest common divisor. For example, 12:18 simplifies to 2:3.

Scaling Ratios

If you know a ratio and one value in an equivalent ratio, you can find the missing value using cross-multiplication.

Frequently Asked Questions

A ratio is simplified by dividing both terms by their greatest common divisor. For example, 12:18 simplifies to 2:3.

If you know a ratio and one value in an equivalent ratio, you can find the missing value using cross-multiplication.

It simplifies a ratio to its lowest terms, or scales a ratio to find a missing value.

Yes, scaling a known ratio to find a missing value works for any proportional relationship, including recipes and mixing ratios.

A ratio like 12:18 simplifies to 2:3 by dividing both numbers by their greatest common divisor, which is 6.

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