Rectangle Calculator
Area, perimeter, diagonal and aspect ratio of a rectangle.
Your result will appear here as soon as you add some input.
How to use it
- 1Enter your values in the fields above.
- 2The answer and the working appear immediately below.
- 3Check the working to see the formula with your numbers substituted.
Formulas used
- A = w x h
- P = 2(w + h)
- d = sqrt(w^2 + h^2)
About the Rectangle Calculator
The diagonal comes from the Pythagorean theorem, since the two sides and the diagonal form a right-angled triangle. It is the figure quoted for screen sizes.
Two rectangles with the same diagonal can have very different areas: a 16:9 screen has noticeably less area than a 4:3 screen of the same diagonal.
Questions people ask
Is your figures uploaded to a server?
No. This tool runs entirely in your browser using standard web APIs, so your figures never leaves your device. You can confirm it by opening your browser's network panel while the tool runs, or by disconnecting from the internet after the page has loaded.
Is it free, and do I need an account?
Yes, it is free, and there is no account, no sign-up and no watermark on the result. The project is funded by optional donations.