Perimeter Calculator
Perimeter
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Formula Used
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How It Works
This perimeter calculator uses established formulas to provide accurate results.
The basic rule:
- Rectangle: P = 2(length + width)
- Square: P = 4 × side
- Triangle: P = a + b + c
- Circle (Circumference): C = 2πr = πd
Results are estimates. Consult a professional for critical decisions.
Frequently Asked Questions
What is perimeter?
Perimeter is the total distance around the outside of a two-dimensional shape. You find it by adding up the lengths of all the sides.
What is the difference between perimeter and circumference?
Perimeter is the general term for the distance around any shape. Circumference specifically refers to the perimeter of a circle: C = 2πr or C = πd.
How do you find the perimeter of a rectangle?
Add all four sides, or use the formula P = 2(length + width). Since a rectangle has two pairs of equal sides, you add length and width, then multiply by 2.
How do you find the perimeter of an irregular shape?
Simply add up the lengths of all the sides. There is no shortcut formula for irregular shapes — you must measure and add each side individually.