Paint & Flooring
Carpet Calculator
Work out how much carpet you need. Because carpet comes off a roll of fixed width, this carpet calculator plans the strips for each room, then gives the floor area, the square yards you will actually pay for, carpet pad and the cost.
Result
Enter your measurements and press Calculate. What to buy, the working and the cost will appear here.
How to use the carpet calculator
- Enter each room’s length and width.
- Choose the roll width: 12 ft is standard in the US, 4 m or 5 m in metric markets.
- Keep the trim allowance (about 3 in at each end of every strip) and the pad allowance.
- Add prices per square yard (or square foot) for carpet and pad, then press Calculate.
How carpet is calculated
Carpet is not bought by floor area alone: it comes off a roll of fixed width, so you pay for whole strips. For each room the calculator works out how many strips of the roll width cover the room, in whichever direction uses less carpet, and adds trim at each end:
roll length = strips × (room length + trim)
carpet bought (yd²) = roll length × roll width ÷ 9
A 14 × 12 ft room fits one 12 ft wide strip 14 ft 6 in long: 174 ft², or 19.3 square yards, for a 168 ft² floor.
Worked example: two bedrooms
Two bedrooms of 14 × 12 ft and 11 × 10 ft, carpet from a 12 ft roll at $28 per square yard and pad at $5 per square yard:
- Room 1: 1 strip of 12 ft covers 12 ft; each 14.5 ft long including trim = 14.5 ft
- Room 2: 1 strip of 12 ft covers 11 ft; each 10.5 ft long including trim = 10.5 ft
- Carpet to buy: 25 ft × 12 ft wide = 300 ft² (33.33 yd²)
Carpet to buy: 33.33 yd²; Floor area: 278 ft² (30.89 yd²); Carpet pad: 32.43 yd²; Estimated cost: $1,095.50. Open this example in the calculator.
Square feet to square yards
Carpet is usually priced per square yard. One square yard is 3 × 3 ft, or 9 ft², so divide square feet by 9: a 12 × 15 ft room is 180 ft² = 20 square yards. In metric, carpet is priced per square meter.
Roll width and seams
- Rooms up to 12 ft wide can usually be covered with one strip and no seam.
- Wider rooms need a second strip and a seam; the leftover from that strip is often the main source of waste.
- Pile direction must run the same way on both sides of a seam, which limits how offcuts can be reused.
- Patterned carpet needs extra length to match the pattern across seams; ask the retailer.
Carpet pad and installation
Pad is laid edge to edge without the strip waste, so it is close to the floor area plus a few percent. Installers also use tack strip around the room perimeter and transition strips at doorways; many retailers include these in installation pricing.
Assumptions and limitations
- Each room is planned on its own; installers who plan seams across the whole job may save some carpet.
- Rooms are rectangles. Closets and alcoves can be added as small rooms.
- Stairs are not included; they are usually estimated per step by the installer.
Carpet questions
How many square yards of carpet do I need for a 12 × 12 room?
The floor is 144 ft² (16 yd²). From a 12 ft roll you buy one strip about 12 ft 6 in long, which is 150 ft², or 16.7 yd².
Why is the carpet I buy more than my floor area?
Because rolls come in fixed widths. A 13 ft wide room needs a 12 ft strip plus a 1 ft strip, and the rest of the second strip is waste unless it can be used elsewhere.
How do I convert square feet to square yards?
Divide by 9. 270 ft² is 30 square yards.
Formulas, unit conversions and default values are explained on our methodology page. Results are estimates; check manufacturer data and local codes before you buy or build.