How to use the square footage calculator
- Pick US units to measure in feet, or UK units to measure in metres.
- Choose a shape and enter its measurements. Most rooms are rectangles.
- For L-shaped rooms, open-plan spaces or gardens, click Add another area and enter each part separately. The calculator adds them up.
- Optionally enter a price per square foot or square metre to estimate the cost of flooring, turf, paving or carpet.
Area formulas
Rectangle = length × width Circle = π × (diameter ÷ 2)² Triangle = base × height ÷ 2 Trapezoid = (side a + side b) ÷ 2 × height
For a triangle or trapezoid, the height is measured at right angles to the base (or to the two parallel sides), not along a sloping edge.
Worked example: an L-shaped room (US)
Split the room into a 12 × 10 ft rectangle and a 6 × 4 ft rectangle: 120 + 24 = 144 ft², which is 16 yd² or 13.4 m².
Worked example: an L-shaped room (UK)
A 4 × 3 m area plus a 2 × 1.5 m area: 12 + 3 = 15 m², which is about 161.5 ft².
Area conversions
| From | To | Multiply by |
|---|---|---|
| Square feet (ft²) | Square metres (m²) | 0.0929 |
| Square metres (m²) | Square feet (ft²) | 10.764 |
| Square feet (ft²) | Square yards (yd²) | 0.1111 (÷ 9) |
| Square yards (yd²) | Square metres (m²) | 0.8361 |
| Acres | Square feet (ft²) | 43,560 |
| Hectares | Acres | 2.471 |
Measuring tips
- Measure wall to wall at floor level, and take two measurements of each dimension. Old rooms are rarely perfectly square — use the larger figure.
- Ignore skirting boards or baseboards; measure to the wall.
- For flooring, include the space inside closets and under appliances that will sit on the new floor.
- Once you have the area, the flooring calculator and tile calculator turn it into boxes and tiles to buy.
Frequently asked questions
How do I calculate the square footage of a room?
Measure the length and width in feet and multiply them. A room 12 ft long and 10 ft wide is 12 × 10 = 120 ft². For L-shaped or irregular rooms, split the floor into rectangles, work out each one and add them together.
How many square feet are in a square metre?
One square metre is 10.764 ft², and one square foot is 0.0929 m². To convert square feet to square metres, divide by 10.764.
How do I convert square feet to square yards?
Divide by 9, because a square yard is 3 ft × 3 ft. For example, 180 ft² ÷ 9 = 20 yd². Carpet in the US is often priced per square yard.
How many square feet are in an acre?
An acre is 43,560 ft² (about 4,047 m²). A hectare is 10,000 m², or about 2.47 acres.
How do I measure a room with a bay window or alcove?
Measure the main rectangle first, then add the bay or alcove as a separate section. A square bay is a rectangle; an angled bay is close to a trapezoid. Use “Add another area” for each part.
Is the square footage of a house the same as its floor area?
Not always. Listings usually quote finished, heated living space and follow local measuring standards, which may exclude garages, unfinished basements and areas with low ceilings. This calculator gives the plain geometric area of whatever you measure.