⚖️ Proportion Calculator

It solves proportion equations A:B = C:D. Given three values, it finds the fourth. Common use cases: 1) Adjusting recipe portions proportionally; 2) Map scale distance conversions; 3) Blueprint scaling calculations; 4) Business profit/cost ratio calculations; 5) Chemical solution mixing ratios; 6) Image/video aspect ratio scaling.

Enter three known values in the proportion equation A:B = C:D, leave the unknown field empty, and click Calculate. For example: given 2:3 = 10:X, enter A=2, B=3, C=10, leave D empty, and the calculator finds X=15. Also supports a Scale mode for quick ratio-based scaling.

A fraction represents a single number (e.g., 3/4 = 0.75), while a proportion represents a relationship between two numbers (e.g., 3:4 compares 3 to 4). A proportion can be written as a fraction (3:4 = 3/4), but proportions emphasize the correspondence between two quantities. This tool supports both.

Absolutely not. This tool runs entirely in your browser. All calculations happen locally on your device. No registration required, no data uploaded, and your calculation data stays only in your browser.

Yes. This tool supports integers, decimals, and negative numbers in proportion calculations. For example: -2.5:5 = X:10 gives X=-5. It also supports fraction input (like 1/3), automatically converting to decimal. Results show both decimal and fraction forms.

Switch to 'Scale' mode, enter an original value and a scale factor (e.g., 1.5 means enlarge by 1.5x, 0.5 means reduce by half). Also supports ratio format input (like 3:2), perfect for image resizing, map scale conversions, and similar scenarios.