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MaterialCalc — Carpet & Pad Cost Calculator

Estimate prepared 09/02/2026. Estimates only; verify against your plans before ordering.

Carpet & Pad Cost Calculator

Each needs a transition strip.

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Higher than plank flooring because the 12 ft roll rarely matches the room.

Result

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Carpet is priced by the square yard but rooms are measured in square feet, and it comes off a 12 foot roll — so a room 13 feet wide needs a seam and throws away most of the offcut. That roll width is why carpet carries more waste than any other flooring.

Assumptions used

These are the numbers behind the result. Where one of them is soft, the cost range widens rather than pretending to a precision the data does not have.

Square feet per square yard
9 ft²

Carpet is priced by the square yard while rooms are measured in square feet.

Unit definition — Published product data, checked 09/01/2026

Carpet roll width
12 ft

Carpet comes in 12 ft rolls, so a room wider than 12 ft needs a seam and wastes the offcut.

Home Depot / Lowe's published product data — Published product data, checked 09/01/2026

Carpet waste allowance
0.15

Higher than plank flooring because the roll width rarely matches the room.

Standard industry overage — Industry standard, varies by supplier, checked 09/01/2026

Luxury vinyl plank box coverage
24 ft²

Home Depot / Lowe's published product data — Industry standard, varies by supplier, checked 09/01/2026

Prices verified 09/01/2026 (US national average, big-box retail shelf price and regional ready-mix quotes). Regional adjustment: Blended from RSMeans city cost index bands and BLS construction wage differentials.

The formula

Area = length × width in square feet, plus a 15% allowance. Square yards = square feet ÷ 9. Pad is ordered to the same yardage. A room wider than the 12 ft roll needs a seam, and the strip cut to fill it is largely waste.

Worked examples

20x15 bedroom

Room length: 20 Room width: 15 Doorways: 3 Flooring type: carpet Waste: 15

300 ft² is 38 square yards ordered. At 15 ft wide this room needs a seam off a 12 ft roll.

12x14 room — no seam needed

Room length: 14 Room width: 12 Doorways: 2 Flooring type: carpet Waste: 15

Exactly 12 ft in one direction, so the roll covers it in a single piece. This is the geometry that wastes least.

Whole upstairs, 30x24

Room length: 30 Room width: 24 Doorways: 5 Flooring type: carpet Waste: 15

720 ft², 92 square yards. Multiple seams — worth walking the plan with the installer before they cut.

Choosing materials

  • Twelve feet is the standard roll width, with 15 ft available in some lines. A room 12 ft or narrower in one direction has almost no waste; 13 ft has a great deal.
  • The pad matters more than people expect. An 8 lb rebond pad under a mid-range carpet feels better underfoot and lasts longer than an expensive carpet over a cheap pad.
  • Ask where the seams will fall. A seam across a doorway or in the middle of a main walkway will show and will wear; a good installer plans them along walls and in low-traffic corners.
  • Carpet on stairs is priced separately and per step, not by area. It uses far more material per square foot than a flat floor and it is skilled work.
  • Divide by 9, not by 3. Converting square feet to square yards trips people constantly, and a factor-of-three error is expensive in both directions.

Common questions

How do I convert square feet to square yards?

Divide by 9. A 300 square foot room is 33.3 square yards before waste, or about 38 with a 15% allowance. Carpet is quoted per square yard, so this conversion is where most pricing confusion starts.

How much does carpet cost installed?

Material typically $15 to $35 per square yard for mid-range carpet, plus $5 to $9 for pad and $8 to $12 for installation. A 300 ft² room lands roughly $1,100 to $2,100 all in.

Why does carpet have more waste than other flooring?

Because it comes off a 12 ft roll in one piece. Any room dimension over 12 ft needs a seam, and the strip cut to fill the remainder is usually too narrow to use elsewhere. Fifteen percent is a realistic allowance.

Do I need new carpet pad?

Almost always. Pad compresses over its life and a new carpet over a flattened pad feels wrong and wears fast. Most warranties are also void without new pad of a specified density.

Where will the seams be?

Ask before the carpet is cut. Seams should run along the length of the room, away from main walkways and out of doorways. A seam across a traffic path will show within a year.

How long does carpet last?

Eight to twelve years in a normal household, less in a busy hallway and more in a guest room. Pad quality, vacuuming and whether shoes come off at the door matter more than the carpet grade.

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