Rectangle Perimeter Calculator
Find the perimeter of a rectangle from its length and width instantly with this free geometry calculator in your browser.
Enter Values
Shape
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How to use this calculator
- Enter the length and width.
- Press Calculate.
How it works
Perimeter = 2 × (length + width).
Worked example
4 × 3 m. = 14 m.
Common mistakes
- Adding length and width only once — perimeter counts each twice.
- Confusing perimeter with area; perimeter is a distance, area a surface.
Frequently asked questions
How do I calculate a rectangle's perimeter?
Add the length and width and double it: Perimeter = 2 × (length + width).
What's the difference between perimeter and area?
Perimeter is the distance around the edge (in metres); area is the surface inside (in square metres).
How is perimeter different from area?
Perimeter — 2 × (length + width) — is the distance around the edge in metres; area (length × width) is the space inside in m².
Related tools
- Rectangle Area Calculator
- Square Area Calculator
- Trapezoid Perimeter Calculator
- Triangle Perimeter Calculator
- Rectangular Prism Volume Calculator
- Regular Polygon Area Calculator
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Cite this tool
Zerdly. (2026). Rectangle Perimeter Calculator. Retrieved from https://www.zerdly.com/tools/rectangle-perimeter-calculator/
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.