Math & Science
Rectangle Calculator
Calculate rectangle area, perimeter, diagonal
Created and maintained by: CalcTago Editorial TeamLast updated: 2026-02-08
Formulas and edge cases are reviewed against authoritative references before publication. For methodology, editorial standards, or corrections, use the links below.
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Frequently asked questions
What does the Rectangle Calculator do?
It helps you calculate rectangle area, perimeter, diagonal.
What inputs do I need?
Enter Length and Width.
Are decimals supported?
Yes, you can use decimal values where appropriate.
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About this tool
This Rectangle Calculator turns your inputs into practical results. Provide Length and Width to calculate Area and Perimeter.
Adjust values to compare scenarios and see how sensitive the result is. The calculation uses the numbers as entered, so double-check units and expect small differences from rounding in the displayed totals.