CALCULATE · VISUALIZE · EXPLORE

Rectangle Calculator

Calculate area, perimeter and diagonal.

● Live results · Runs on your device · No sign-up

Your inputs

Area = width × height. Diagonal = √(width² + height²).

Live results

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UNDERSTAND YOUR RESULTS

Rectangle Calculator guide

Calculate area, perimeter and diagonal.

How to use this tool

Enter Width, Height.
Change a value to update the results and illustration. Check any validation message before using the output.
Copy the results or download CSV. Reset restores the example values.

A worked example

Width 8 and height 5 give area 40 and perimeter 26.

How it works

Area = width × height. Diagonal = √(width² + height²).

Frequently asked questions

How should I interpret the illustration?

It is a visual aid, not a replacement for the numeric output. Some charts compare values with different units, and those magnitudes are not directly comparable.

Can I use the result without checking the inputs?

Check units, signs, assumptions and rounding first. The tool cannot know whether the values you enter describe the real situation correctly.