Enter two different ratios to calculate the proportion of one ratio to another. This calculator solves for X of equal proportions.

Proportion Formula

The following formula is used to calculate the missing value of a proportion.

X = Z/W * Y
  • Where X is the missing value
  • Z/W is the first proportion
  • Y is the denominator of the second proportion

Proportion Definition

In simple terms, a proportion is a relationship between two different quantities. These quantities are typically represented as two different ratios.

These ratios comprise a numerator (top number) and a denominator (bottom number). This term is typically referred to as a fraction.

How to Calculate a Proportion

Let’s say you have 7 pieces of pie out of 12 total pieces. This ratio is 7/12. Now you look over and see your friend has 3 pieces of pie out of 12, which is a ratio of 3/12. Now you want to compare the proportion of your slices to his slices, or 7/12: 3/12.

The first step is to convert these to a solid integer proportion, you typically need to convert to the least common denominator and then you cross out the denominators and you have your proportion of 7/1: 3/1.


What is a proportion?

A proportion is a term used to describe the ratio of fractions to one another.

What’s the difference between a fraction and a proportion.

A fraction is a ratio of one number to another, and a proportion is a ratio of fractions.