Square Footage Calculator
Add up the area of one or many rooms, include a waste allowance, and get the total in square feet, square metres, square yards and acres — plus an instant material-cost estimate.
Square footage = length × width. Measure each room in the same unit, multiply length by width, and add the rooms together. For materials, multiply the total by (1 + waste %) — typically +10% — to know how much to buy.
Tip: break L-shaped or irregular spaces into rectangles, add each as a separate area, and the totals add up automatically.
How to Measure Square Footage
For any rectangle, the area is simply length × width. The only rules are to measure both sides in the same unit and to be consistent: if you measure in feet, your answer is in square feet (ft²); if you measure in metres, it is in square metres (m²). To get the area of a whole home or project, measure each room as its own rectangle and add the results — that is exactly what the calculator above does when you add a new area.
For L-shaped or irregular spaces, draw a line that splits the footprint into two or more rectangles, measure each one, and enter them as separate areas. Round measurements up slightly rather than down, and remember that the figure you can buy is the measured area plus a waste allowance for cuts, breakages and pattern matching.
Converting Between Square Feet, Metres & Yards
The same area can be written in several units. These are the exact conversion factors used by this calculator:
- 1 ft² = 0.092903 m² = 0.1111 yd²
- 1 m² = 10.7639 ft² = 1.19599 yd²
- 1 yd² = 9 ft² = 0.836127 m²
- 1 acre = 43,560 ft² = 4,046.86 m² = 0.4047 hectare
How Floor Area Is Measured Around the World
The unit a home is advertised in — and even which space counts — changes from country to country:
| Unit | Where it's used | Equivalent |
|---|---|---|
| Square foot (ft²) | US, UK, India, Canada, Gulf listings | 0.0929 m² |
| Square metre (m²) | Europe, Australia, China, global SI | 10.764 ft² |
| Square yard / gaj | India, Pakistan | 9 ft² · 0.836 m² |
| Tsubo (坪) | Japan (property & land) | ≈ 35.6 ft² · 3.306 m² |
| Cent | South India (land) | 435.6 ft² · 40.47 m² |
| Acre | US, UK, India (land) | 43,560 ft² · 4,047 m² |
| Hectare (ha) | Metric land area, farming | 10,000 m² · 2.471 acres |
Tip: always check whether a quoted area is net (usable internal space) or gross (including walls). France's loi Carrez and the international IPMS standards exist precisely to make that clear.
Frequently Asked Questions
How do you calculate square footage?
Square footage is length × width. Measure a rectangular room's length and width in the same unit (feet, metres, etc.), then multiply them. For a 12 ft × 10 ft room, the area is 120 square feet. To find the square footage of a whole house or project, calculate each rectangular area separately and add them together.
How do I find the square footage of an L-shaped or irregular room?
Break the space into simple rectangles. Draw a line to split the L-shape (or any irregular footprint) into two or more rectangles, measure each one, calculate length × width for each, and add the results. This calculator lets you add a separate area for each rectangle so the totals add up automatically.
How much extra (waste) should I add for flooring or materials?
Order 5–15% more than the measured area. Straight-lay flooring or tile usually needs 5–10%; diagonal layouts need about 15%; herringbone and complex patterns can need 20–25%. The extra covers cuts, mistakes and future repairs, and buying it all at once means the colour and batch match.
How do you convert square feet to square metres?
Multiply square feet by 0.0929 to get square metres, or divide square metres by 0.0929 (multiply by 10.764) to go the other way. For example, 1,000 sq ft = 92.9 m², and 100 m² = 1,076 sq ft. This calculator shows every result in square feet, square metres, square yards and acres at the same time.
How is floor area measured in different countries?
The unit changes by country: the US, UK, India, Canada and the Gulf usually advertise homes in square feet, while most of Europe, Australia, China and Japan use square metres. India and Pakistan also use the square yard (gaj); Japan uses the tsubo (坪 ≈ 3.31 m²); land is measured in acres (imperial) or hectares (metric). France's "loi Carrez" even defines exactly which space counts toward a flat's legal area, so always check whether a figure is net (usable) or gross (including walls).
Sources & Methodology
Each area is calculated as length × width in the chosen unit and summed across all rooms. Totals are converted using exact factors (1 ft² = 0.09290304 m², 1 yd² = 0.83612736 m², 1 acre = 4046.8564224 m²). The waste factor multiplies the measured total by (1 + waste%), and material cost multiplies the waste-adjusted area by the price per unit area entered.
Standards and figures reviewed June 2026.