Diagonal Measurement Calculator
Calculate the diagonal of a rectangle, screen, room, panel, or rectangular object using its width and height. Get the result instantly in your preferred unit.
Add the horizontal measurement of the rectangular area.
Add the vertical measurement using the same unit.
See the corner-to-corner distance and related measurements.
The calculator applies the Pythagorean theorem. Square the width and height, add those values, then take the square root of the total.
The height is 2.40 times the width, producing a diagonal angle of 67.38° from the horizontal.
Useful for checking whether walls and frames are square, measuring TV and monitor screen sizes, planning floor layouts, sizing panels, calculating room diagonals, and estimating corner-to-corner cable runs.
Use the same unit for both width and height. For construction checks, compare both corner-to-corner diagonals: matching values indicate that a rectangular frame is square.
How do I calculate a rectangle diagonal?
Square the width and height, add the results, and take the square root.
Can I calculate a TV screen diagonal?
Yes. Enter the screen width and height in inches to get its diagonal size in inches.
Does the unit affect the formula?
No. Any unit works as long as the width and height use the same unit.
Results are estimates generated locally in your browser using standard mathematical formulas. They are for informational and educational purposes only and are not a substitute for verification in coursework, examinations or professional contexts requiring certified accuracy. VisionVix accepts no liability for decisions based on this tool's output.
This calculator is intended for general planning and estimation. Verify critical construction or manufacturing measurements with calibrated tools.
