How the square footage calculator works
Square footage is the area of a flat surface measured in square feet. For a rectangular room it is simply length multiplied by width. The calculator also returns the perimeter, the distance around the room, which you need for baseboard and crown molding.
Switch to metric and the same dimensions convert at the edges, so the area stays exact. Square yards are shown because carpet is often priced that way in the US.
Formula and assumptions
- L
- room length, wall to wall
- W
- room width, wall to wall
Assumptions and limits
- Assumes a rectangular area; irregular shapes should be split into rectangles.
- Returns the true surface area with no waste allowance. Add allowance in the material calculator.
Worked example
A bedroom measures 12 ft by 10 ft.
- 12 × 10 = 120 sq ft of floor.
- 120 ÷ 9 = 13.33 sq yd.
- Perimeter = 2 × (12 + 10) = 44 ft.
These are the calculator’s default values, so the live result above matches this example until you change an input.
How to measure correctly
- Measure wall to wall at floor level, not along the baseboard top.
- Round each dimension up to the next inch rather than down.
- Split L-shaped or open-plan spaces into rectangles, calculate each, and add them.
- Include closets and alcoves you will floor; leave out built-ins you will not.
- Convert inches to decimal feet by dividing by 12 (10 ft 6 in = 10.5 ft).
Common room sizes
| Room | Square feet | Square yards | Square meters | Perimeter |
|---|---|---|---|---|
| 10 × 10 ft | 100 sq ft | 11.1 sq yd | 9.3 sq m | 40 ft |
| 10 × 12 ft | 120 sq ft | 13.3 sq yd | 11.1 sq m | 44 ft |
| 12 × 12 ft | 144 sq ft | 16.0 sq yd | 13.4 sq m | 48 ft |
| 12 × 14 ft | 168 sq ft | 18.7 sq yd | 15.6 sq m | 52 ft |
| 14 × 16 ft | 224 sq ft | 24.9 sq yd | 20.8 sq m | 60 ft |
| 16 × 20 ft | 320 sq ft | 35.6 sq yd | 29.7 sq m | 72 ft |
Square Footage Calculator FAQ
How do I calculate square footage for an L-shaped room?
Split the L into two rectangles, find each area (length × width), and add them. Make sure no strip of floor is counted twice where the rectangles meet.
How do I convert inches to feet for square footage?
Divide inches by 12 before multiplying. A room 11 ft 6 in by 9 ft 3 in is 11.5 × 9.25 = 106.4 sq ft.
How many square feet are in a square yard or square meter?
A square yard is exactly 9 sq ft (3 ft × 3 ft). A square meter is about 10.764 sq ft, because 1 ft = 0.3048 m exactly.
Should I include closets in the square footage?
Include any area that will receive the same material. For flooring that usually means closets; for a rug or furniture plan it may not.
Is square footage the same as how much flooring to buy?
No. Square footage is the area to cover. Flooring, tile, and carpet orders add an allowance for cuts and round up to whole boxes or roll lengths.
How do I find the square footage of a room with a bay window or angled wall?
Treat the main room as a rectangle and calculate the extra section separately. A triangle is half of base × height; a bay can usually be split into a rectangle and two triangles.