Proportion Calculator
[wpcalc_proportion] The proportion calculator above solves for a missing value in a ratio using cross-multiplication, so you can scale recipes, convert measurements, or solve math homework problems in seconds. Enter three known values from your proportion (A/B = C/D) to solve for the fourth. What Is the Proportion Calculator? A proportion states that two ratios […]
[wpcalc_proportion]
The proportion calculator above solves for a missing value in a ratio using cross-multiplication, so you can scale recipes, convert measurements, or solve math homework problems in seconds. Enter three known values from your proportion (A/B = C/D) to solve for the fourth.
What Is the Proportion Calculator?
A proportion states that two ratios are equal, written as A/B = C/D. This calculator takes any three of the four values and solves for the missing one using cross-multiplication, which is useful for scaling recipes, converting units, solving similar-triangle problems, and other everyday ratio math.
How to Use the Proportion Calculator
- Enter the three known values in your proportion (A, B, and C, or whichever three you know).
- Leave the unknown value blank.
- Click Calculate to solve for the missing value instantly.
How Proportions Are Solved
To solve A/B = C/D for an unknown value, cross-multiply so that A × D = B × C, then divide to isolate the missing variable. For example, if 2/5 = x/20, cross-multiplying gives 5x = 40, so x = 8. For a refresher on the underlying concept, see the Khan Academy lessons on ratios and proportions.
Proportions vs Percentages
Percentages are really just proportions out of 100, so the two concepts are closely related. If you need to express a ratio as a percentage instead, try our Percentage Calculator.
Frequently Asked Questions
What is an example of a proportion in real life?
Scaling a recipe is a common example: if a recipe for 4 people needs 2 cups of flour, you can set up a proportion to find how much flour you need for 10 people (2/4 = x/10, so x = 5 cups).
What’s the difference between a ratio and a proportion?
A ratio compares two quantities (like 2:5), while a proportion is a statement that two ratios are equal (like 2/5 = 4/10). In other words, a proportion is made up of two equal ratios.