Proportion Calculator

Calculate proportions and solve proportion problems.

Calculator

Enter Your Values

Enter the first ratio (a:b)

Enter the second ratio (c:d), leave d empty to solve for it

Table of Contents

1 What is a Proportion?
2 How to Calculate Proportions
3 Proportion Calculations - Practical Examples
Definition

What is a Proportion?

A proportion is an equation that states that two ratios are equal. It is written in the form a:b = c:d, where a, b, c, and d are numbers. For example:

Example:
2:4 = 3:6
This means that 2 is to 4 as 3 is to 6
Steps

How to Calculate Proportions

To solve a proportion:

  1. 1
    Write the proportion in the form a:b = c:d
  2. 2
    Cross-multiply: a × d = b × c
  3. 3
    Solve for the unknown value

For example, to solve 2:4 = 3:x:

Example:
2 × x = 4 × 3
2x = 12
x = 6
Examples

Proportion Calculations - Practical Examples

Example 1 Simple Proportion

Solve 3:6 = 4:x

3 × x = 6 × 4
3x = 24
x = 8

Example 2 Recipe Scaling

If 2 cups of flour make 12 cookies, how many cups are needed for 36 cookies?

2:12 = x:36
2 × 36 = 12 × x
72 = 12x
x = 6

Example 3 Map Scale

If 1 inch on a map represents 50 miles, how many miles does 3.5 inches represent?

1:50 = 3.5:x
1 × x = 50 × 3.5
x = 175

Tools

Mathematics Calculators

Significant Figures Cube Root Antilog Lcd Decimal To Fraction

Need other tools?

Can't find the calculator you need? Contact us to suggest other mathematical calculators.