Perimeter Formulas by Shape
The perimeter is the total distance around the outside of a 2D shape.
| Shape | Formula |
|---|---|
| Square | P = 4s |
| Rectangle | P = 2(l + w) |
| Triangle | P = a + b + c |
| Circle | C = 2πr |
| Trapezoid | P = a + b + c + d |
⊡ Perimeter Calculator (Multiple Shapes)
Perimeter
Frequently Asked Questions
What is the perimeter of a 5×8 rectangle? ▼
P = 2(5+8) = 2×13 = 26 units.
What is the perimeter of an equilateral triangle with side 6? ▼
P = 3 × 6 = 18 units. An equilateral triangle has all three sides equal.
What is the difference between perimeter and area? ▼
Perimeter measures the boundary length of a shape (in linear units like cm or m). Area measures the surface enclosed by the shape (in square units like cm² or m²).