Math

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Perimeter of a Rectangle Calculator.

Calculate 2(width + height).

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01

Set your values

Results update as you type.

Perimeter: 16

Perimeter

0.000000

Results update automatically as you type.

Use Cases

Framing and Construction

Determine the amount of trim, baseboard, or fencing needed for a rectangular area by calculating its perimeter.

Example: A room 12 ft by 15 ft needs 54 ft of baseboard.

Gardening and Landscaping

Find the length of edging or border material required for a rectangular garden bed or lawn.

Example: A garden 8 m by 5 m requires 26 m of edging.

Frequently Asked Questions

How do I calculate the perimeter of a rectangle?
Add the width and height, then multiply by 2. The formula is P = 2 × (width + height). This calculator does that for you automatically.
What units should I use for width and height?
Use any consistent unit, such as inches, feet, centimeters, or meters. The perimeter will be in the same unit you enter.
Can I use this calculator for a square?
Yes, a square is a rectangle with equal width and height. Enter the same value for both fields to get its perimeter.

Tips & Common Mistakes

Tips

  • Ensure width and height are in the same unit before calculating.
  • Double-check your measurements for accuracy, especially if buying materials.
  • For irregular shapes, break them into rectangles and calculate each perimeter separately.
  • Remember that perimeter is a linear measurement, not an area.

Common Mistakes to Avoid

  • Using different units for width and height, which leads to incorrect results.
  • Forgetting to multiply the sum by 2, resulting in half the actual perimeter.
  • Confusing perimeter with area; perimeter measures distance around, not the surface.

Last updated: August 13, 2026