Proportion Calculator
Free online proportion calculator tool.
About Proportion Calculator
The Proportion Calculator solves for a missing variable in a pair of equivalent ratios (A/B = C/D). This is often known as the Rule of Three and is incredibly useful for scaling recipes, calculating exchange rates, and resizing images.
How Proportion Calculator Works
- Step 1: Enter Knowns: Enter the values for A, B, and C. For instance, if 2 apples (A) cost $4 (B), and you want to know the cost of 5 apples (C).
- Step 2: Calculate: The calculator performs cross-multiplication (B × C) and divides by A to find the missing value D (which would be $10).
Frequently Asked Questions
What is cross-multiplication?
Cross-multiplication is a mathematical method used to solve proportions. You multiply the numerator of the first fraction by the denominator of the second, and vice versa. It states that if A/B = C/D, then A×D = B×C.
What is a real-world example of using this?
If a recipe calls for 2 cups of flour (A) to make 10 cookies (B), and you want to make 25 cookies (C), you can use this tool to find out how many cups of flour (D) you need.