What is perimeter?

Perimeter is the distance all the way around a 2D shape, the sum of the lengths of all its sides. For a rectangle it's 2 × (length + width).

Examples

• A 5 cm by 3 cm rectangle: 2 × (5 + 3) = 16 cm.
• A square with 4 cm sides: 4 × 4 = 16 cm.

Quick facts

• Perimeter is a length, measured in cm, m, etc.
• Area (the space inside) is different, measured in square units.