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Rectangle Calculator

Result

Area60.0000
Perimeter32.0000
Diagonal11.6619
↗ Math

Rectangle Calculator Calculate area, perimeter, and diagonal of a rectangle. — free online calculator.

Formula

Area = l × w; Perimeter = 2(l+w); Diagonal = √(l²+w²)
  • Rectangle Calculator calculates its result from Length, Width. It uses the formula Area = l × w; Perimeter = 2(l+w); Diagonal = √(l²+w²). Change any input to recalculate the result instantly.
  • The main inputs are Length, Width. Enter them in the units and format shown in the calculator.
  • Keep comparable quantities in compatible units whenever the formula combines or compares them.
  • Changing any input above recalculates the result with the same calculation engine used by this page.

Example: Rectangle

Inputs
  • Length: 10
  • Width: 6

Using Length = 2, Width = 3, the calculated result is 3.6055512755.

Sample result: Calculating…

Frequently asked questions

What does the Rectangle calculate?

Rectangle Calculator Calculate area, perimeter, and diagonal of a rectangle. — free online calculator.

Which values should I enter?

Enter Length, Width using the units and format shown beside each field.

What formula does this calculator use?

The calculator uses the following relationship: Area = l × w; Perimeter = 2(l+w); Diagonal = √(l²+w²).

Why might my result differ from another source?

Results can differ when another source uses different units, rounding rules, conventions or assumptions. Compare the inputs and definitions before comparing results.

Does the result update automatically?

Yes. Changing an input updates the result using the same calculation engine shown on this page.

Page information

Updated: October 10, 2026