Ratio Calculator

Simplify ratios to simplest form or solve for unknown values in proportions (A : B = C : D).

Solve proportion A : B = C : D. Leave exactly one unknown field blank or type 'x' to solve for it. Or enter only A and B to simplify the ratio.

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How to Use the Ratio Calculator

Enter the required values in the fields above and click Calculate. All calculations are executed directly inside your web browser using proven mathematical formulas, ensuring instantaneous results and 100% privacy without transmitting your numbers to remote servers.

Mathematical Formula

A / B = C / D => A ร— D = B ร— C (Cross-multiplication)

Worked Example

To solve 4 : 5 = 20 : D => D = (5 ร— 20) รท 4 = 25.

Important Notes & Limitations

Ratio values must be non-zero real numbers.

Frequently Asked Questions

Find the greatest common divisor (GCD) of the terms and divide each term by that common factor.