Proportion Solver
Enter a, b, and c, choose a direct or inverse proportion, and calculate x in your browser.
A QUICK WALKTHROUGH
How to use this tool
- Choose direct or inverse proportion.
- Enter the values for a, b, and c.
- Choose decimal places from 0 to 12 and calculate x.
Direct and inverse formulas
Direct proportion uses x ÷ b = c ÷ a, which gives x = b × c ÷ a. Inverse proportion uses x × c = a × b, which gives x = a × b ÷ c.
Decimal rounding
Choose from 0 through 12 decimal places. The calculation keeps full JavaScript number precision until the displayed result is rounded.
Private browser calculation
Validation and calculation happen locally in your browser. Your values are not uploaded or stored by this page.
GOOD TO KNOW
Common questions
What is a direct proportion?
A direct proportion keeps the ratio between corresponding values constant: x ÷ b = c ÷ a.
What is an inverse proportion?
An inverse proportion keeps the product constant: x × c = a × b.
Can I enter negative or decimal values?
Yes. Negative and decimal values are supported as long as all inputs are finite and the divisor is not zero.
How precise is the result?
You can display from 0 through 12 decimal places. Results use JavaScript number arithmetic.