How to use the carpet calculator
- Measure the room's length and width at the widest points, into door openings to the middle of the door.
- Pick the roll width. Most US carpet is 12 ft wide; some is 13 ft 2 in or 15 ft. Ask the store if you're not sure.
- Add the floor area of closets, a hallway or a bay window as extra square feet.
- Read off square yards, which is how carpet and pad are usually priced, and how many strips the installer will cut.
Why you buy more carpet than the floor area
Carpet comes off a roll, so a room is covered in full-width strips. A 14 ft wide room with 12 ft carpet needs two strips, and most of the second one is offcut. The calculator lays the strips both ways and picks the one that uses less carpet, then adds 3 inches at each end of every strip for trimming at the walls.
strips = room width ÷ roll width, rounded up
carpet (sq ft) = strips × roll width × (room length + 0.5 ft)
square yards = square feet ÷ 9
Carpet for common room sizes
With 12 ft wide carpet. Real orders can be a little lower when the installer uses offcuts for closets.
| Room | Floor sq ft | Floor sq yd | Strips | Carpet to buy (sq yd) |
|---|---|---|---|---|
| 10 × 10 ft | 100 | 11.1 | 1 × 10.5 ft | 14.0 |
| 10 × 12 ft | 120 | 13.3 | 1 × 10.5 ft | 14.0 |
| 12 × 12 ft | 144 | 16.0 | 1 × 12.5 ft | 16.7 |
| 12 × 14 ft | 168 | 18.7 | 1 × 14.5 ft | 19.3 |
| 12 × 15 ft | 180 | 20.0 | 1 × 15.5 ft | 20.7 |
| 14 × 16 ft | 224 | 24.9 | 2 × 14.5 ft | 38.7 |
| 15 × 20 ft | 300 | 33.3 | 2 × 15.5 ft | 41.3 |
| 20 × 20 ft | 400 | 44.4 | 2 × 20.5 ft | 54.7 |
Pad, tack strip and seams
- Pad is laid edge to edge, so you only need the floor area plus about 5%.
- Tack strip goes around the room's perimeter, except at doorways.
- Seams are where two strips meet. Keep them out of traffic paths and run them toward the main window so they're less visible. Pile direction must match on both sides.
- Stairs: each stair takes roughly a strip 3 ft wide and 1.5 ft long. Count them separately.
Frequently asked questions
How many square yards of carpet do I need for a 12x12 room?
A 12 × 12 ft room is 16 square yards of floor. With 12 ft wide carpet and 3 inches of trim at each end you buy one strip 12.5 ft long, about 16.7 square yards.
How do I convert square feet to square yards for carpet?
Divide square feet by 9. A 200 sq ft room is 22.2 square yards.
How much extra carpet should I buy?
Carpet waste depends on the roll width more than a fixed percentage. Rooms close to the roll width waste almost nothing; a room 13 ft wide with 12 ft carpet wastes nearly half of the second strip. That is why the calculator works in strips.
How much carpet pad do I need?
Pad does not need to match the roll, so buy the floor area plus about 5%. A 12 × 12 room needs about 17 square yards of pad.