How Much Carpet Do I Need? Square Yards by Room Size
Multiply the room's length by its width and divide by 9 to get square yards of floor. You'll buy a little more than that, because carpet comes off a roll in full-width strips. A 12 × 12 ft room is 16 square yards of floor and needs about 16.7 square yards of 12 ft carpet. The carpet calculator works out the strips for any room.
Why the order is bigger than the floor
Most carpet is sold in 12 ft wide rolls, and some in 13 ft 2 in or 15 ft. The installer cuts strips the full width of the roll and adds about 3 inches at each end for trimming at the walls. A room 12 ft wide or less needs one strip. A room 13 or 14 ft wide needs two, and much of the second strip becomes offcut, unless you turn the strips the other way.
Example: a 12 × 14 ft room. Run one 12 ft wide strip the long way, 14 ft plus 6 inches of trim: that's 174 sq ft, or 19.3 square yards, against 18.7 square yards of floor.
strips = room width ÷ roll width, rounded up
carpet to buy = strips × roll width × (room length + 0.5 ft) ÷ 9
Carpet needed by room size
The calculator picks whichever direction uses less carpet. Pad is the floor area plus 5%.
| Room | Floor (sq yd) | 12 ft roll (sq yd) | 15 ft roll (sq yd) | Pad (sq yd) |
|---|---|---|---|---|
| 10 × 10 ft | 11.1 | 14.0 | 17.5 | 11.7 |
| 10 × 12 ft | 13.3 | 14.0 | 17.5 | 14.0 |
| 11 × 12 ft | 14.7 | 15.3 | 19.2 | 15.4 |
| 12 × 12 ft | 16.0 | 16.7 | 20.8 | 16.8 |
| 12 × 13 ft | 17.3 | 18.0 | 20.8 | 18.2 |
| 12 × 15 ft | 20.0 | 20.7 | 20.8 | 21.0 |
| 13 × 14 ft | 20.2 | 36.0 | 22.5 | 21.2 |
| 14 × 16 ft | 24.9 | 38.7 | 27.5 | 26.1 |
| 15 × 18 ft | 30.0 | 41.3 | 30.8 | 31.5 |
| 16 × 20 ft | 35.6 | 44.0 | 55.0 | 37.3 |
| 20 × 20 ft | 44.4 | 54.7 | 68.3 | 46.7 |
How much carpet do I need for stairs?
Each stair takes a piece as wide as the stair and long enough to cover the tread, the riser and about 2 inches wrapped over the nose. For a 3 ft wide stair with a 7.5 inch riser and 10 inch tread, that's 3 × 19.5 in, or about 4.9 sq ft per step.
| Steps | Sq ft | Sq yd |
|---|---|---|
| 3 | 15 | 1.6 |
| 7 | 34 | 3.8 |
| 13 | 63 | 7.0 |
| 14 | 68 | 7.6 |
A typical full flight of 13 or 14 steps needs about 7 to 8 square yards before waste. Pile must run down the stairs on every step, so stairs often can't use offcuts from the rooms. Ask the installer to measure stairs, landings and curved steps before you order.
How much does carpet cost?
Carpet ranges from about $20 per square yard for basic polyester to $55 or more for thick nylon or wool. Pad adds about $3 to $8 per square yard. These totals use the carpet you'd actually buy from the table above, plus pad at $5 per square yard. Prices vary by region and store, so check local quotes.
| Room | Basic ($20/sq yd) | Mid ($35/sq yd) | Premium ($55/sq yd) |
|---|---|---|---|
| 10 × 12 ft | $350 | $560 | $840 |
| 12 × 12 ft | $420 | $670 | $1,000 |
| 12 × 15 ft | $520 | $830 | $1,240 |
| 14 × 16 ft | $900 | $1,480 | $2,260 |
| 16 × 20 ft | $1,070 | $1,730 | $2,610 |
Installation usually adds $1 to $2 per square foot of floor, more for stairs, and removal of old carpet is often extra. Some stores include basic installation with the purchase, so compare the installed price.
Square feet to square yards
Carpet is priced per square yard in the US, and 1 square yard is 9 square feet. So a carpet at $3 per sq ft costs $27 per square yard. Always compare prices in the same unit, and check whether the price includes pad and installation.
Measuring tips
- Measure at the widest point of each wall and into each doorway, to the middle of the door.
- Add closets as separate pieces. An installer can often cover them with offcuts from the main strips.
- Seams should run toward the main window and out of high-traffic paths, and the pile direction must match on every piece.