How carpet is sold
Broadloom carpet is made in rolls, usually 12 feet wide in the United States, sometimes 13.5 or 15 feet. You buy a length of roll, not the exact area of your room. A room narrower than the roll width needs one piece; a wider room needs two or more strips joined by seams, and the leftover width is often wasted.
The calculation
- Choose the direction of the strips: along the room’s length or its width.
- Count the strips: room dimension across the roll ÷ roll width, rounded up.
- Cut length = other dimension + about 3 inches at each end for trimming.
- Carpet to buy = strips × roll width × cut length, divided by 9 for square yards.
The calculator tries both directions and keeps the one that uses less carpet.
Example
A 15 × 11.5 ft bedroom fits within a 12 ft roll. One cut of 15.5 ft gives 12 × 15.5 = 186 sq ft, or 20.7 sq yd, for 19.2 sq yd of floor (7% waste). At $30 per sq yd for carpet, $5 for pad and $7 for installation, the room costs about $865.
| Room size | 12 ft roll | Seams |
|---|---|---|
| 11 × 14 ft | 1 cut of 14.5 ft | none |
| 13 × 14 ft | 2 cuts of 14.5 ft or 2 of 13.5 ft | one |
| 12 × 20 ft | 1 cut of 20.5 ft | none |
Seams and waste
- Run seams away from doorways and the main traffic path, and parallel to the light from windows.
- All strips must run with the pile in the same direction, or the color will look different.
- Leftover pieces can carpet a closet or a stair landing, but patterned carpet needs extra length to match the pattern repeat.
Pad and installation
Pad (underlay) is priced per square yard of floor area. Installers usually charge per square yard of carpet installed, and add fees for stairs, furniture moving and removal of old flooring. Ask whether the quote includes tack strips, transitions and disposal.