Student resources
Grades 4-9
Area and Perimeter Formulas for Students
Perimeter measures distance around a shape. Area measures the space inside a shape. Keep units consistent before calculating.
Key ideas
- Rectangle area = length x width.
- Rectangle perimeter = 2 x length + 2 x width.
- Triangle area = base x height / 2.
- Circle area = pi x radius squared.
Common Formulas
| Shape | Area | Perimeter or circumference |
|---|---|---|
| Square | side x side | 4 x side |
| Rectangle | length x width | 2 x length + 2 x width |
| Triangle | base x height / 2 | add all side lengths |
| Circle | pi x radius x radius | 2 x pi x radius |
Practice questions
Find the area of a rectangle with length 8 and width 3.
Calculation: 8 x 3 = 24
Answer: 24 square units
Find the perimeter of a square with side length 6.
Calculation: 4 x 6 = 24
Answer: 24 units
Find the area of a triangle with base 10 and height 4.
Calculation: 10 x 4 / 2 = 20
Answer: 20 square units
Find the circumference of a circle with radius 5 using pi = 3.14.
Calculation: 2 x 3.14 x 5 = 31.4
Answer: 31.4 units