Carpet off the roll
Carpet for rooms is where the flooring calculator begins here (for a staircase, see the stair carpet page). Enter each room’s length and width, pick the roll width your shop sells, and set the extra length added to every strip for trimming at the walls (it starts at 4 in or 10 cm). The calculator lays strips of the roll’s width side by side across the room, in whichever direction needs the least carpet, and for an L-shaped room also tries cutting it into two rectangles each way.
The result is the length to buy, the number of strips (each extra strip is a seam), and the offcuts: what you pay for but don’t lay. Each area is worked out on its own, because each room is cut from the roll separately; a fitter may still use the offcuts from one room for a closet or a landing.
Choosing the roll width
A room that is just wider than the roll is the expensive case: the second strip must run the full length for a narrow band. Two tables at the foot of the page, one in feet and one in metres, give the roll length for common rooms on each width. When a room is a little wider than 12 ft or 4 m, the wider roll often saves both carpet and a seam. Shaw’s planning guide says larger rooms may need extra material for seaming and asks you to agree the pattern direction and the seams with the installer before the carpet is cut; the strip layout here is a starting point for that conversation.
Price
Choose the price unit that matches the shop: per square foot or square yard in the US, per square metre in the UK and Europe. The cost covers all the carpet you buy, offcuts included, but not underlay, gripper or fitting.
Carpet to buy by room and roll width
Strips laid in whichever direction needs less carpet, each the room's length plus 4 in (10 cm) for trimming, offcuts not reused.
| Room | 12 ft roll | 15 ft roll |
|---|---|---|
| 10 × 10 ft | 10′ 4″ · 13.8 sq yd · 24% offcut | 10′ 4″ · 17.2 sq yd · 55% offcut |
| 10 × 12 ft | 10′ 4″ · 13.8 sq yd · 3% offcut | 10′ 4″ · 17.2 sq yd · 29% offcut |
| 12 × 14 ft | 14′ 4″ · 19.1 sq yd · 2% offcut | 12′ 4″ · 20.6 sq yd · 10% offcut |
| 13 × 15 ft | 26′ 8″ · 35.6 sq yd · 1 seam · 64% offcut | 13′ 4″ · 22.2 sq yd · 3% offcut |
| 14 × 16 ft | 28′ 8″ · 38.2 sq yd · 1 seam · 54% offcut | 16′ 4″ · 27.2 sq yd · 9% offcut |
| 16 × 20 ft | 32′ 8″ · 43.6 sq yd · 1 seam · 23% offcut | 32′ 8″ · 54.4 sq yd · 1 seam · 53% offcut |
| Room | 4 m roll | 5 m roll |
|---|---|---|
| 3 × 3 m | 3.1 m · 12.4 m² · 38% offcut | 3.1 m · 15.5 m² · 72% offcut |
| 3 × 4 m | 3.1 m · 12.4 m² · 3% offcut | 3.1 m · 15.5 m² · 29% offcut |
| 3.5 × 4.5 m | 4.6 m · 18.4 m² · 17% offcut | 3.6 m · 18 m² · 14% offcut |
| 4 × 5 m | 5.1 m · 20.4 m² · 2% offcut | 4.1 m · 20.5 m² · 2% offcut |
| 4.5 × 5 m | 9.2 m · 36.8 m² · 1 seam · 64% offcut | 4.6 m · 23 m² · 2% offcut |
| 5 × 6 m | 10.2 m · 40.8 m² · 1 seam · 36% offcut | 6.1 m · 30.5 m² · 2% offcut |
Sources, checked September 2026: Shaw Floors, carpet installation planning (12 and 15 ft rolls); Cormar Carpets, planning and measuring (4 and 5 m widths).