Perimeter · Year 5

In Year 5 you learn: perimeter of rectangles with a formula and finding a missing side from the perimeter.

The perimeter of a shape is the distance all the way round it: add the lengths of all its sides. For a rectangle, perimeter = 2 × (length + width). Perimeter is a length, so it is measured in cm, m or km.

Key facts

• Perimeter is the distance all the way round a shape: add up all its sides.
• Rectangle: area = length × width; perimeter = 2 × (length + width).
• A square has 4 equal sides, so its perimeter is 4 × the side.
• Rectilinear shapes: work out any missing sides from the others first.

Worked examples

Other years

• Perimeter · Year 3
• Perimeter · Year 4
• Perimeter · Year 6