Perimeter Calculator
Calculate the perimeter (total boundary length) of common 2D shapes.
Rectangle
Circle
Triangle
Polygon
Perimeter
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Select shape and enter dimensions
Perimeter Formulas
| Shape | Formula | Notes |
|---|---|---|
| Rectangle | P = 2(l + w) | Sum of all four sides |
| Circle (Circumference) | C = 2 pi r | Also C = pi d |
| Triangle | P = a + b + c | Sum of three sides |
| Square | P = 4s | Four equal sides |
| Regular Polygon | P = n x s | n = number of sides |
What is Perimeter?
Perimeter is the total distance around the outside of a 2D shape. For a circle, it's called circumference. It's measured in linear units like meters, feet, or centimeters.