Proportion Calculator
Enter three terms of a proportion and calculate the fourth automatically.
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How to use
- 1Enter three values, leave one field blank and check the solved proportion.
About
Proportion calculator with a built-in result check.
Proportion calculator
Solve proportions in the form A / B = C / D and find the missing value.
Enter three terms and leave exactly one field blank. The tool uses cross multiplication and checks the result.
Integers and decimals are supported as long as denominators are not zero.
Examples
- 2 / 3 = 8 / 12 → D = 12.
- 5 / 10 = 3 / 6 → proportion confirmed.
Limitations
- Leave exactly one term blank.
- B and D cannot be zero.
How to use
- 1Enter three values.
- 2Leave the unknown blank.
- 3Review the answer and check.
Frequently asked questions
Which formula is used?
The unknown is isolated with cross multiplication: A × D = B × C.
Can I use decimals?
Yes. Enter a decimal using the separator accepted by your browser.
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