How to use the area calculator
- Choose metres or feet, and the shape.
- Enter the measurements. For a room, measure wall to wall at floor level.
- For several identical areas — like matching bedrooms — enter how many.
Area formulas
| Shape | Formula |
|---|---|
| Rectangle or square | length × width |
| Circle | π × (diameter ÷ 2)² |
| Triangle | ½ × base × height (height measured at right angles to the base) |
Conversions
| From | To | Multiply by |
|---|---|---|
| square feet | square metres | 0.09290304 |
| square metres | square feet | 10.7639 |
| square yards | square feet | 9 |
| square yards | square metres | 0.83612736 |
Using your area
Once you have the area, the next step is usually working out materials. Use the tile calculator, laminate calculator or paint calculator — they include waste allowances and turn the area into boxes or tins to buy.
Common mistakes to avoid
- Mixing units. Convert inches to feet (÷ 12) before multiplying.
- Measuring a slanted side as the triangle height. The height must be at right angles to the base.
- Counting overlaps twice when you split an L-shape into rectangles.
Measuring an awkward shape? See how to measure an irregular area.
Frequently asked questions
How do I calculate square footage?
Multiply the length by the width, both in feet. A room 12 ft by 15 ft is 12 × 15 = 180 square feet. For a circle, use π × (diameter ÷ 2)²; for a triangle, ½ × base × height.
How do I convert square feet to square metres?
Multiply square feet by 0.09290304 (one square foot is exactly 0.09290304 m²). To go from square metres to square feet, multiply by about 10.764.
How do I measure an L-shaped room?
Split it into two rectangles, measure each, and add the areas together. Use the “How many” box if you have several identical areas.
How many square feet is a square yard?
Nine — a square yard is 3 ft × 3 ft. Carpet is sometimes priced per square yard, so the calculator shows square yards too.
Last updated 10 November 2026. Found a mistake? Tell us.