Area Calculator
Work out the area of a rectangle, triangle, circle, trapezium, parallelogram or ellipse in m², ft², acres or hectares, with the formula.
New: please check your results.
- Area
- 12 m²
- Perimeter
- 14 m
What it does
Find the area of a flat shape from its measurements. Choose the shape, enter its sizes in metres, feet or any other unit, and see the area in square metres or square feet. Convert it to acres, hectares or anything else with the Convert box.
How to use it
- Shape
The shape you're measuring. For an L-shaped room or garden, split it into rectangles and add their areas together.
- Length
For a rectangle: the longer side. For a square, enter the same number for length and width.
- Width
For a rectangle: the shorter side.
- Base
For a triangle or parallelogram: the length of the bottom side.
- Height
The straight-up (perpendicular) height from the base to the top, not the length of a sloping side.
- Top side (a)
For a trapezium: one of the two parallel sides.
- Bottom side (b)
The other parallel side.
- Radius
For a circle: the distance from the centre to the edge, which is half the diameter.
- Half the long axis
For an ellipse: from the centre to the furthest edge (half the full length).
- Half the short axis
From the centre to the nearest edge (half the full width).
Common uses
- Measuring a room for flooring or carpet.
- Working out the size of a garden, lawn or plot.
- Working out tiles for a floor or wall. Try the Tile Calculator
- Working out paint for the walls. Try the Paint Calculator
- Working out the volume of a 3D shape. Try the Volume Calculator
The formula
Rectangle: length × widthTriangle: base × height ÷ 2Parallelogram: base × heightTrapezium: (a + b) ÷ 2 × heightCircle: π × radius²Ellipse: π × a × bWhere:
- π
- pi, about 3.14159
- a, b
- for an ellipse, half its length and half its width
Measure every side in the same unit, or let the calculator convert: you can mix metres and feet.
Worked example
For a rectangle 4 m long and 3 m wide:
- Area: 4 m × 3 m = 12 m²
- Perimeter: 2 × (4 m + 3 m) = 14 m
Questions people ask
How do I work out the area of an L-shaped room?
Split it into two rectangles, work out the area of each, and add them together. For more awkward shapes, split them into rectangles and triangles.
How do I convert square metres to square feet?
Multiply by 10.764. One square metre is about 10.76 square feet, and one square foot is about 0.093 square metres. The Convert box under the results does this for any unit.
What's the difference between area and perimeter?
Area is the space inside a shape, measured in square units such as m². Perimeter is the distance around the edge, measured in ordinary units such as metres. You'd use area for carpet and perimeter for skirting board.
Last checked 26 October 2026