Square footage is the area of a rectangular space, calculated by multiplying its length by its width — both measured in feet. It is the standard unit for room size, flooring, tiling, and paint estimates in the United States.
The formula
sq ft = length (ft) × width (ft)
For a 12-foot by 10-foot room: 12 × 10 = 120 sq ft.
How to measure a room
- Measure the longest wall (length) in feet. Include any alcoves or closets if you want the total floor area.
- Measure the perpendicular wall (width) in feet.
- Multiply. That is the square footage.
- For L-shaped or irregular rooms, break the space into rectangles, calculate each, and add them together.
Measuring in inches: If your measurements are in inches, divide each by 12 first (or divide the final product by 144, since 12² = 144).
Practical examples
Example 1 — Flooring estimate
A rectangular bedroom is 13 ft × 11 ft.
13 × 11 = 143 sq ft
When buying flooring, add 10% for waste and cuts: 143 × 1.1 = 157.3 sq ft (order 160 sq ft).
Example 2 — L-shaped living/dining room
The living area is 16 × 12 ft (192 sq ft) and the dining nook is 8 × 8 ft (64 sq ft).
192 + 64 = 256 sq ft total.
Example 3 — Tile estimate
A bathroom floor is 9 ft × 7 ft = 63 sq ft. Tiles are sold in boxes covering 15 sq ft each.
63 ÷ 15 = 4.2 boxes → buy 5 boxes (always round up, and add 10% for cuts near edges and grout lines).
Common room sizes for reference
| Room type | Typical size (sq ft) |
|---|---|
| Small bedroom | 100–120 sq ft |
| Standard bedroom | 120–200 sq ft |
| Primary bedroom | 200–300 sq ft |
| Standard bathroom | 40–100 sq ft |
| Small living room | 150–200 sq ft |
| Standard living room | 250–400 sq ft |
| One-car garage | 200–240 sq ft |
Square feet to square meters
If you need to convert a square footage result to square meters, divide by 10.764 (since 1 m² = 10.764 sq ft). A 120 sq ft room is approximately 11.1 m².