How to calculate square footage
For a rectangle or square room, multiply length by width in feet. A 12 ft × 10 ft bedroom is 120 sq ft. Convert inches to feet first by dividing by 12: 12 ft 6 in = 12.5 ft.
| Shape | Formula | Example |
|---|---|---|
| Rectangle / square | length × width | 12 × 10 = 120 sq ft |
| Triangle | base × height ÷ 2 | 10 × 8 ÷ 2 = 40 sq ft |
| Circle | 3.1416 × radius² | 10 ft across: 3.1416 × 5² = 78.5 sq ft |
| L-shaped room | split into 2 rectangles, add them | (12 × 10) + (8 × 6) = 168 sq ft |
Typical room sizes in the US
| Room | Typical size | Square feet |
|---|---|---|
| Small bedroom | 10 × 10 ft | 100 |
| Primary bedroom | 14 × 16 ft | 224 |
| Living room | 16 × 20 ft | 320 |
| Kitchen | 10 × 15 ft | 150 |
| Bathroom | 5 × 8 ft | 40 |
| One-car garage | 12 × 22 ft | 264 |
| Two-car garage | 22 × 22 ft | 484 |
How much flooring to buy
Add 5–10% extra for cuts and mistakes on a simple straight layout, and 15% or more for diagonal, herringbone or tile with lots of cuts. Flooring is sold by the box, so divide the total by the square feet per box and round up. Keep a spare box for future repairs.
Unit conversions: 1 square yard = 9 sq ft (carpet is often priced per square yard). 1 square meter = 10.764 sq ft.
Step-by-step with pictures in words: how to calculate square footage.
Square Footage Calculator FAQs
How do I calculate square feet in feet and inches?
Turn inches into decimal feet (inches ÷ 12), then multiply. 11 ft 6 in × 9 ft 3 in = 11.5 × 9.25 = 106.4 sq ft. The calculator does this for you with separate ft and in boxes.
How do I find the square footage of a house?
Measure each room (or the outside walls) and add them up. Real estate listings usually count finished, heated living space and leave out garages and unfinished basements.
How many square feet is a 12x12 room?
144 square feet (16 square yards).
How much does flooring cost per square foot?
Very roughly: vinyl plank $2–$5, laminate $1.50–$4, carpet $2–$6, hardwood $5–$12 per sq ft for materials. Installation often adds $2–$6 per sq ft.