What is a ratio in simplest form?

A ratio with no common divisor left: divide every part by their greatest common divisor, e.g. 84 : 126 becomes 2 : 3.

How do I solve a proportion?

Cross-multiply: for a/b = x/c, x = a × c ÷ b. The calculator shows each step.

Ratio & Proportion Calculator

Work with ratios three ways: reduce a ratio to simplest form, scale it up or down, or find the missing term of a proportion with cross-multiplication steps.

How to use the ratio & proportion calculator

Choose the calculation type.
Enter the ratio parts or the known values.
Read the answer with its steps.

Examples

Simplify 84 : 126

Answer: 2 : 3

Scale 2 : 3 by 5

Answer: 10 : 15

3/4 = x/20

Answer: x = 15