How much carpet do I need?
Type the room’s length and width and pick the roll width. The carpet calculator lays whole strips the way that wastes least and gives the carpet to buy, the length off the roll, the seams and the cost.
- Carpet to buy
- 34.67 yd²
Buy 34.67 yd² of carpet, 26 ft off the roll.
- Length off the roll
- 26 ft
- Strips
- 2
- Seams
- 1
- Strips run
- Along the room width
- Room area
- 21.67 yd²
- Room area, square feet
- 195 ft²
- Leftover
- 13 yd²
Carpet to buy: 34.67 yd². Buy 34.67 yd² of carpet, 26 ft off the roll.
How to calculate
Carpet calculator: how many square yards and linear feet of carpet to buy for a room, cut in whole strips from a 12 or 15 ft roll, with the seams, the leftover and the cost.
Example with the default inputs (Room length 15 ft, Room width 13 ft, Roll width 12 ft): Buy 34.67 yd² of carpet, 26 ft off the roll.
Method: Strips = room side across the strips ÷ roll width, rounded up; carpet to buy = strips × strip length × roll width, for the direction that buys less.
- The room is a rectangle; split an L-shaped room into rectangles.
- Strips are full roll width and run the full length or width of the room; a cut-off piece is not reused to fill another gap.
- Add a few inches per strip for trimming at the walls if your fitter asks for it.
Worked examples
Each example is checked against the calculator on every build.
- Room length 15 ft, Room width 13 ft, Roll width 12 ft, Price per square yard $30.00 gives Strips 2, Carpet to buy 34.67 yd², Length off the roll 26 ft, Cost $1,040.00, Strips run Along the room width.Source: Wikipedia, Carpet (carpets are commonly made 12 or 15 ft wide in the US and 4 or 5 m in Europe), https://en.wikipedia.org/wiki/Carpet (retrieved 2026-10-03)
- Room length 20 ft, Room width 12 ft, Roll width 12 ft gives Strips 1, Seams 0, Carpet to buy 26.67 yd², Leftover 0 yd².Source: Wikipedia, Carpet (carpets are commonly made 12 or 15 ft wide in the US and 4 or 5 m in Europe), https://en.wikipedia.org/wiki/Carpet (retrieved 2026-10-03)
- Room length 19.69 ft, Room width 14.76 ft, Roll width 4 m gives Strips 2, Carpet to buy 43.06 yd², Room area 32.29 yd², Leftover 10.76 yd².Source: Wikipedia, Carpet (carpets are commonly made 12 or 15 ft wide in the US and 4 or 5 m in Europe), https://en.wikipedia.org/wiki/Carpet (retrieved 2026-10-03)
How it works
Carpet is cut in strips the full width of the roll. The strips can run along the room length or along the room width:
- Along the length: strips = room width ÷ roll width, rounded up; carpet = strips × room length × roll width.
- Along the width: strips = room length ÷ roll width, rounded up; carpet = strips × room width × roll width.
The calculator uses the direction that buys less carpet; on a tie, along the length. Then:
- Carpet to buy = that carpet area, in square yards (or m²).
- Length off the roll = strips × strip length.
- Seams = strips − 1.
- Room area = length × width; leftover = carpet to buy − room area.
- Cost = carpet to buy in square yards × the price per square yard, when you type a price.
Roll widths. 12 ft, 15 ft, 4 m, 5 m, or a width you type.
Rules
Room sides and a custom roll width are from 1 cm to 1 km. A leftover piece is never reused to fill another strip.
Output format
Areas show to 2 decimals in square yards and square feet (US) or square metres (Metric); the length off the roll in feet (US) or metres (Metric) to 2 decimals; strips and seams as whole numbers; the cost in money. Typed sizes are read back as exact decimals, so the strip count is exact, and each value is rounded half up once.
Worked examples by hand
A 15 × 13 ft room, 12 ft roll, $30 per square yard. Along the length: 13 ÷ 12 → 2 strips × 15 × 12 = 360 ft². Along the width: 15 ÷ 12 → 2 strips × 13 × 12 = 312 ft². Buy 312 ft² = 34.67 yd², two 13 ft strips (26 ft off the roll), one seam. Room 195 ft²; leftover 117 ft². Cost 34.667 × $30 = $1,040.
A 20 × 12 ft room, 12 ft roll. Along the length: 12 ÷ 12 = 1 strip × 20 × 12 = 240 ft² = 26.67 yd², no seam, no leftover.
A 6 × 4.5 m room, 4 m roll. Along the length: 2 strips × 6 × 4 = 48 m². Along the width: 2 strips × 4.5 × 4 = 36 m², the smaller. Room 27 m²; leftover 9 m².
Other questions people ask
How do I calculate how much carpet I need?
Carpet comes on a roll, usually 12 ft wide. Divide the room width by 12 and round up to get the strips, then multiply strips × room length × 12 ft. Do the same the other way round and buy the smaller amount.
Why do I need more carpet than the room area?
Each strip is a full roll width. A 13 ft wide room needs two 12 ft strips, so 11 ft of the second strip is left over. A 15 × 13 ft room is 195 ft² (21.67 yd²) but takes 312 ft² (34.67 yd²) of carpet from a 12 ft roll.
How many square yards of carpet for a 12 × 12 room?
Exactly 16 square yards from a 12 ft roll: one strip 12 ft long, 144 ft² ÷ 9 = 16 yd², with no seam.
What widths does carpet come in?
In the US, usually 12 or 15 ft; in Europe, 4 or 5 m. A wider roll can cover a room in one piece with no seam.
How do I price carpet per square yard?
Multiply the square yards to buy by the price per square yard. 34.67 yd² at $30 is $1,040. Include pad and fitting in the price if you want the total.
Should I add extra for trimming?
Fitters often add a few inches to each strip to trim at the walls. Add that to the room length before you type it if your fitter asks for it.