Length and Perimeter
Perimeter is the total distance around the outside of a shape. We find it by adding all the side lengths together.
What You Need to Know
Key Concept Diagram
Perimeter is the total length of all sides of a shape
For a rectangle: P = 2 × (length + width)
Perimeter is measured in units of length: mm, cm, m, km
Shapes with the same area can have different perimeters
Key Vocabulary
Perimeter
The total distance around the outside of a shape
Length
Distance measured in a straight line
Millimetre (mm)
A small unit of length; 10 mm = 1 cm
Centimetre (cm)
A unit of length; 100 cm = 1 m
Knowledge Check
Select the correct answer for each question. Click "Check Answer" to see if you are right.
Question 1
A rectangle has length 8 cm and width 3 cm. What is its perimeter?
Question 2
A square has perimeter 20 cm. What is the length of one side?
Question 3
Which unit would you use to measure the perimeter of Australia?
Key Concepts Summary
- ●Perimeter is the total length of all sides of a shape
- ●For a rectangle: P = 2 × (length + width)
- ●Perimeter is measured in units of length: mm, cm, m, km
- ●Shapes with the same area can have different perimeters