Measure all the way around shapes like a superstar!
Perimeter is the total distance all the way around the outside of a shape.
Think of it like putting a fence around a garden — you add up all the sides!
A rectangle has two pairs of equal sides: length (l) and width (w).
Example: l = 6 cm, w = 4 cm
P = 2 × (6 + 4) = 2 × 10 = 20 cm
Or: P = l + l + w + w = 6 + 6 + 4 + 4 = 20 cm ✓
A square has 4 equal sides. If each side = s:
Example: s = 5 cm → P = 4 × 5 = 20 cm
For shapes with lots of different sides, just add them all up!
Example: sides 3 cm, 4 cm, 5 cm, 3 cm
P = 3 + 4 + 5 + 3 = 15 cm
Tip: label each side as you go so you don't miss any!
If you know the perimeter and some sides, you can find the missing side by subtracting.
Example: Rectangle, P = 18 cm, l = 6 cm
w = (18 ÷ 2) − 6 = 9 − 6 = 3 cm
Or: missing side = P − sum of known sides
Find the perimeter of a rectangle with length 7 cm and width 4 cm.
Find the perimeter of a square with side 8 cm.
A rectangle has perimeter 20 cm and length 6 cm. Find the width.
A garden is 9 m long and 6 m wide. How much fencing is needed?
A shape on squared paper has sides: top 4, right 3, bottom 4, left 3.
Use P = 2 × (l + w) to find each perimeter.
Use P = 4 × s to find each perimeter.
The perimeter is given. Work out the missing side.
Count the units around the outside of each shape on the grid.
Read each problem and find the perimeter.