Diagonal Calculator
Calculate the diagonal of a rectangle or square using the Pythagorean theorem. Input the width and height to get the diagonal length.
Published by:
isCalculator Editorial Team
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How to use this tool?
This calculator computes the diagonal length of a rectangle given its width and height.
- Enter Width in the first input field (e.g., 3).
- Enter Height in the second input field (e.g., 4).
- Click Calculate Diagonal.
- The result shows the diagonal length and the step-by-step formula using
d = √(w² + h²).
Note: Inputs must be positive numbers. The result is displayed with 4 decimal places. No specific unit system is required—use any consistent unit (e.g., inches, cm).
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Frequently Asked Questions
The diagonal d of a rectangle with width w and height h is given by d = √(w² + h²), derived from the Pythagorean theorem.
Yes. For a square, width and height are equal. The diagonal is side × √2.
The calculator works with any units as long as width and height are in the same unit. The result will be in that same unit.
