How to use this tool
- Pick the shape.
- Choose your unit and enter the measurements.
- Read the area in square feet, square metres, square yards and acres.
Area formulas
| Shape | Formula |
|---|---|
| Rectangle or square | length × width |
| Triangle | ½ × base × height |
| Circle | π × radius² |
| Trapezoid | ½ × (a + b) × height |
Measuring a room
For flooring or paint, measure the longest walls at floor level. An L-shaped room can be split into two rectangles, worked out separately and added. Flooring suppliers usually suggest buying 5–10% extra to allow for cuts and waste.
Units
For a circle, measure straight across through the centre and halve it to get the radius. For a triangular corner of a garden, the height is the straight-line distance from the base to the far point, measured at a right angle to the base.
US and UK property listings often use square feet, while most other countries use square metres. In Pakistan and India, land is also measured in marla and kanal or gaj, which vary by region, so check the local definition. One acre is 43,560 square feet. To convert lengths, use the unit converter.
Frequently asked questions
How do I calculate square feet?
Multiply length by width in feet. A 10 × 12 ft room is 120 sq ft.
How do I convert square feet to square metres?
Divide by 10.764. 500 sq ft is about 46.45 m².
How do I find the area of a circle?
Multiply π (3.1416) by the radius squared. A radius of 3 m gives 28.27 m².
How many square feet is an acre?
43,560 square feet.