Proportion Calculator
Solve proportions quickly, accurately, and step-by-step. Find the missing value (x) using cross multiplication.
Result
Step-by-Step Solution
Calculation History
Proportion Examples
Click on any example below to auto-fill the calculator and see the solution.
How to Use Proportion Calculator
Solving a proportion is easy with this tool. Follow these simple steps:
- Enter three known values: You must have three numbers to find the missing one. Decimals and simple fractions (like 1/2) are supported.
- Leave the unknown value blank: The calculator will identify the empty field as the variable 'x'.
- Click Calculate: The system will instantly compute the missing value using cross multiplication.
- Review the answer: The result will be displayed in decimal and fraction formats, along with a verification check.
- Check the step-by-step solution: Scroll down to see exactly how the formula was applied to arrive at the answer.
Proportion Formula
A proportion represents two equal ratios. It is typically written as:
To solve for any missing value, we use the Cross Multiplication method:
Depending on which value is missing, the formulas are:
- Find A: A = (B × C) / D
- Find B: B = (A × D) / C
- Find C: C = (A × D) / B
- Find D: D = (B × C) / A
Frequently Asked Questions
A proportion is a mathematical statement that two ratios or fractions are equal. It is typically written in the format a:b = c:d or a/b = c/d.
Enter the three known values in the proportion calculator and leave the unknown value blank. The calculator will use cross multiplication to find the missing variable.
Yes, our Proportion Calculator fully supports decimal values. For example, you can enter 2.5 : 5 = 10 : x.
Yes, you can enter simple fractions like 1/2 or 3/4 directly into the input fields. The calculator will automatically convert them to decimals internally for the calculation.
Cross multiplication involves multiplying the numerator of the first fraction by the denominator of the second, and setting it equal to the product of the first denominator and the second numerator (A × D = B × C).
Absolutely. A ratio equation (A : B = C : D) is mathematically identical to a proportion fraction (A / B = C / D). You can solve any missing part of the ratio here.
Yes, after computing the result, the calculator automatically runs a verification check to ensure that A/B exactly equals C/D with the new value inserted.
Yes, this tool is 100% free to use directly in your browser without any hidden fees, registrations, or limitations.