Geometry · free · no sign-up
Area Calculator
Calculate the area of five common shapes and see a drawing of the shape as you enter dimensions.
About the Area Calculator
Calculate the area of five common shapes and see a drawing of the shape as you enter dimensions.
How to use the Area Calculator
- Choose a shape: Square, Rectangle, Circle, Triangle or Trapezoid.
- Enter the dimensions that appear (such as side, length and width, radius, base and height).
- Press Calculate area to see the area and the drawing.
Formula and method
Square: s² · Rectangle: l × w · Circle: π × r² · Triangle: ½ × b × h · Trapezoid: ½ × (a + b) × h
Worked example
A circle with radius 5: π × 5² = 78.54 square units.
When to use the Area Calculator
- Working out how much flooring, paint, turf or fabric you need.
- Finding the area of common shapes for school or work.
- Comparing plots of land or rooms.
Common mistakes to avoid
- Mixing units, for example feet for one side and inches for the other.
- Forgetting to subtract areas that will not be covered, such as windows.
- Not adding a little extra for waste when buying materials.
Tips
- Area is measured in square units (cm², m², ft²). Keep the units consistent.
- For irregular shapes, split them into rectangles and triangles and add the areas.
Frequently asked questions
How do I convert area units?
Square the length conversion factor. For example, 1 m² = 10,000 cm² because 1 m = 100 cm.
How do I find the area of an irregular shape?
Split it into simple shapes such as rectangles and triangles, work out each area and add them up.
What is the difference between area and perimeter?
Area is the space inside a shape, in square units. Perimeter is the distance around its edge.