Measure the room and pick the roll width. Carpet comes off a roll 12′ wide (13½′ and 15′ on some styles), so a room is covered in strips: you get how much to buy in square yards and linear feet, where the seam falls, the waste and the pad.
Carpet to buy
34.7 sq yd26 linear ft of a 12′ roll, in 2 strips across the room · 1 seam · 42% waste · 20.2 sq yd of pad
Every roll width for this room
Quick answer: carpet comes off a roll 12′ wide, so you buy the roll’s width by the length you need, not the room’s area. A room up to 12′ in one direction takes one strip: a 14′ × 12′ room needs 18.7 sq yd with no waste. A 14′ × 13′ room needs two strips and a seam, 34.7 sq yd for 20.2 of floor, unless the carpet comes in a 13½′ or 15′ roll.
How to use the carpet calculator
- Measure the room wall to wall, into the doorway to where the carpet will stop.
- Pick the roll width the carpet you like comes in: 12′ is standard, some styles come 13½′ or 15′ wide.
- Read what to buy in square yards and linear feet, the strips and the seams, the waste and the pad, and how every roll width compares for your room. Copy link keeps the result.
How carpet is measured
- By the roll. The standard US carpet width is 12′, with 13½′ and 15′ in some styles (JP Flooring). You buy linear feet of roll, and the price is per square yard: 9 sq ft.
- In strips, all the same way. A room wider than the roll is covered in strips cut along it, every one laid in the same direction so the pile matches across the seam. The last strip is cut down to fit, and you pay for the width you cut off.
- Both ways round. The strips can run along the room or across it; the calculator tries both and buys the one that takes less carpet, and says so when the other way saves a seam.
- Pad goes under in pieces, so it is the room’s own area.
Carpet by room size and roll width
Square yards to buy, and the seams:
| Room | 12′ roll | 13½′ roll | 15′ roll |
|---|---|---|---|
| 10′ × 10′ | 13.3, no seam | 15, no seam | 16.7, no seam |
| 12′ × 10′ | 13.3, no seam | 15, no seam | 16.7, no seam |
| 12′ × 12′ | 16, no seam | 18, no seam | 20, no seam |
| 14′ × 12′ | 18.7, no seam | 21, no seam | 20, no seam |
| 14′ × 13′ | 34.7, 1 seam | 21, no seam | 21.7, no seam |
| 16′ × 14′ | 37.3, 1 seam | 42, 1 seam | 26.7, no seam |
| 18′ × 15′ | 40, 1 seam | 45, 1 seam | 30, no seam |
| 20′ × 16′ | 42.7, 1 seam | 48, 1 seam | 53.3, 1 seam |
A room just wider than the roll is the expensive case: a 13′ room on a 12′ roll pays for 24′ of width.
Three worked examples
A 14′ × 13′ bedroom on a 12′ roll. Two strips of 13′ across the room, 26 linear ft: 34.7 sq yd for 20.2 sq yd of floor, 42% cut off, and one seam. In a 13½′ or 15′ roll the same room is one piece with no seam.
A 16′ × 15′ living room on a 15′ roll. One strip, 16 linear ft: 26.7 sq yd, no seam and no waste, plus 26.7 sq yd of pad.
A 24′ × 11′ bonus room on a 12′ roll. Two 11′ strips across the room fill it exactly: 29.3 sq yd with one seam. One 24′ strip along it would be 32 sq yd with no seam: more carpet, no seaming.
Common carpet mistakes
- Buying the room’s area. A 13′ room on a 12′ roll takes two widths. Count strips, not square feet.
- Forgetting the doorway and the closet. Measure into the doorway to where the carpet stops, and add the closet as its own strip.
- Turning a strip to save carpet. A piece laid the other way shows as a different shade. Every strip runs the same direction.
- A seam across a busy path. Where there is a choice, keep the seam out of the doorway and the main walkway.
Hard floor instead? The flooring calculator counts boxes of laminate or vinyl plank, and the rug size calculator sizes a rug for it. See the room furnished in the free 2D room planner.
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Carpet questions
How much carpet do I need?
Count the strips: the room’s width ÷ the roll’s width, rounded up, each as long as the room. Multiply the strips by the length and the roll’s width for square feet, and divide by 9 for square yards. The calculator tries the strips both ways and picks the one that takes less.
How wide is a roll of carpet?
12′ is the standard width in the US. Some styles also come 13½′ or 15′ wide, which covers a wider room in one piece.
How do I convert square feet to square yards?
Divide by 9: a square yard is 3′ × 3′. A 12′ × 12′ room is 144 sq ft, or 16 sq yd.
How much carpet for a 12×12 room?
16 sq yd off a 12′ roll: one strip 12′ long, with no seam and no waste.
Where do carpet seams go?
Where one roll width ends: 12′ from the wall the first strip starts at. The calculator draws it. Where you can, keep a seam out of the doorway and the main path through the room.
How much carpet pad do I need?
The room’s area in square yards: pad goes down in pieces and does not have to match, so it has no roll waste.