Area and perimeter
Perimeter
The perimeter is the total distance all the way around the edge of a 2D shape. It is measured in units of length, such as cm or m.
How to find the perimeter
1. Work out the length of any sides that are not labelled. 2. Add together the lengths of all the sides.
Worked examples
A rectangle
- The rectangle is 7 cm long and 3 cm wide.
- Add all four sides: 7 + 3 + 7 + 3.
Answer: Perimeter = 20 cm
A shape made of straight sides
- The sides are 4 cm, 2 cm, 3 cm, 1 cm, 1 cm and 3 cm.
- Add them all together: 4 + 2 + 3 + 1 + 1 + 3.
Answer: Perimeter = 14 cm
Where you see this in real life
- Working out how many fence panels are needed around a garden.
- Measuring the edging needed around a picture frame.
- Finding how much ribbon goes around the edge of a card.
Key words
- Perimeter
- The total distance around the edge of a 2D shape.
- Area
- The amount of surface a shape covers.
- 2D shape
- A flat shape, like a rectangle or triangle.