# How much carpet do I need?

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.

- Page: https://www.acalculator.org/construction/carpet-calculator
- JSON spec: https://www.acalculator.org/construction/carpet-calculator.json
- Version: 08aae345eb1f

## Default answer

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.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| l | Room length | The longer side of the room, wall to wall. |
| w | Room width | The shorter side of the room, wall to wall. |
| r | Roll width | The width of the carpet roll. |
| rw | Custom roll width | The width of the roll, if not listed. |
| p | Price per square yard | The price of the carpet per square yard, with pad and fitting if you like. Leave empty to skip. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| buy | Carpet to buy | Strips × strip length × roll width. |
| linear | Length off the roll | Strips × strip length, the length cut from the roll. |
| strips | Strips | Whole roll widths side by side. |
| seams | Seams | Strips − 1. |
| layout | Strips run | Which way the strips run. |
| room | Room area | Room length × width. |
| roomFeet | Room area, square feet | Room length × width in square feet. |
| leftover | Leftover | Carpet to buy − room area. |
| cost | Cost | Carpet to buy in square yards × the price. |

## 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.

## Assumptions

- 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

1. l = 4.572, w = 3.9624, r = 12ft, p = $30.00 gives strips = 2, buy = 28.985748, linear = 7.9248, cost = $1,040.00, layout = 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).
2. l = 6.096, w = 3.6576, r = 12ft gives strips = 1, seams = 0, buy = 22.29673, leftover = 0. 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).
3. l = 6, w = 4.5, r = 4m gives strips = 2, buy = 36, room = 27, leftover = 9. 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).

## FAQ

### 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.

## Sources

- Wikipedia, Carpet: carpets are commonly made in widths of 12 or 15 ft in the US and 4 or 5 m in Europe, retrieved 2026-10-03. https://en.wikipedia.org/wiki/Carpet
- NIST Special Publication 811 (2008), Appendix B: 1 ft = 0.3048 m exactly, 1 yd² = 9 ft² = 0.83612736 m², retrieved 2026-10-03. https://www.nist.gov/pml/special-publication-811