Measure a space before you buy for it
Flooring, carpet, paint, tiles, turf and rent are all priced by the square foot, so a quick, accurate area is worth having. Measure the length and width of a room, multiply, and you have its square footage. Odd shapes and whole floors take a little more care, which is where this calculator helps.
Choose a rectangle, several rooms, a circle or a triangle. The answer comes in square feet with square metres, square yards and acres alongside, and an optional price per square foot turns it into a total cost.
How to measure and calculate
- Measure the length and width of the space at floor level, wall to wall.
- Pick the shape. For an L-shaped room or a whole floor, choose Several rooms and enter each rectangle.
- Choose the unit you measured in. Several rooms works in feet.
- Add a price per square foot if you want a cost.
- Read the square footage and the conversions. Copy the result for your quote or shopping list.
Square footage formulas
rectangle = length × width
circle = π × (diameter ÷ 2)²
triangle = base × height ÷ 2
1 sq ft = 0.09290304 sq m; 1 sq yd = 9 sq ft; 1 acre = 43,560 sq ftMeasurements in inches, yards, metres or centimetres are converted to feet first, then squared. That is why 144 square inches make one square foot: 12 inches times 12 inches.
Worked example: three rooms of flooring
A homeowner is pricing new flooring for three rooms: 15 by 12 feet, 12 by 10 feet and 10 by 8 feet, at $4.50 a square foot.
- 15 × 12 = 180 sq ft
- 12 × 10 = 120 sq ft
- 10 × 8 = 80 sq ft
- Total: 380 sq ft, which is 35.3 sq m
The three rooms come to 380 sq ft, so the flooring costs 380 × $4.50 = $1,710.00 before fitting. Most fitters suggest buying 5% to 10% extra to allow for cuts and waste.
Quick conversions
| Square feet | Square metres | Square yards |
|---|---|---|
| 100 | 9.29 | 11.11 |
| 250 | 23.23 | 27.78 |
| 500 | 46.45 | 55.56 |
| 1,000 | 92.9 | 111.11 |
| 2,000 | 185.81 | 222.22 |
| 43,560 | 4,046.86 | 4,840 (one acre) |
Measuring mistakes to avoid
- Adding feet and inches as decimals. 10 feet 6 inches is 10.5 feet, not 10.6.
- Measuring over skirting or furniture. Measure the open floor, wall to wall.
- Forgetting closets and alcoves. Measure them as extra rectangles.
- Buying exactly the area. Patterned flooring and tiles need more waste allowance than plain ones.
- Using area for volume jobs. Concrete, gravel and soil need depth too; try the concrete calculator.
Frequently asked questions
How do I calculate square footage?
Multiply the length by the width, both in feet. A room 15 feet long and 12 feet wide is 15 × 12 = 180 square feet. For an irregular space, split it into rectangles, work out each one and add them up. Choose Several rooms above to do that in one go.
How do I convert square feet to square metres?
Multiply square feet by 0.0929. So 380 square feet is about 35.3 square metres. To go the other way, multiply square metres by 10.764, so a 20 square metre room is about 215 square feet. The calculator shows square metres, square yards and acres next to every square foot answer.
How do I convert inches to square feet?
Either convert both measurements to feet first, by dividing by 12, and then multiply, or multiply the inches together and divide by 144. A tile 18 by 24 inches is 432 square inches, which is 3 square feet. Choose Inches as the unit and the calculator does it.
How many square feet are in an acre?
An acre is 43,560 square feet, or about 4,047 square metres. A plot 100 feet by 435.6 feet is exactly one acre, and an American football field without the end zones is a little over one acre. For land, choose a rectangle in feet or yards and read the acres line under the answer.
How much extra flooring should I buy?
Fitters often suggest 5% to 10% extra for plain flooring laid straight, and more for patterns, diagonal layouts or awkward rooms. Work out the square footage here, multiply by 1.1 for 10% extra, and round up to whole boxes or rolls.
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