How to measure for your carpet project
- Measure the room in feet. Measure room length and width at the longest points, including any alcoves or closets you want to carpet. For L-shaped rooms, split the floor into rectangles, calculate each, and add the totals. Measure doorways too -- carpet typically wraps through the threshold.
- Choose a waste allowance and roll width. Select 10% waste for a simple rectangular room with no pattern, 15% for stairs or hallways, and 20% for rooms with many corners or a patterned carpet that needs pattern-matching at seams. Pick the roll width your supplier stocks -- 12 ft is the most common. The calculator returns square yards (how carpet is priced) and the linear feet you pull off the roll.
- Convert to square yards and order. Take the square-yard total to your flooring store or use it when ordering online. Also note the linear-foot figure -- that tells your installer how much roll to cut. Always buy a small remnant for future repairs, because dye lots change between production runs.
How the carpet calculator works
Carpet pricing uses square yards, not square feet, because broadloom carpet has historically been sold off wide rolls measured in yards. The math: multiply room length by width to get square feet, multiply by (1 + waste fraction) to account for cuts and seams, then divide by 9 to convert to square yards (9 sq ft = 1 sq yd). Linear feet -- the running length you pull off the roll -- is the waste-adjusted area divided by the roll width, rounded up to the next whole foot, because suppliers cut in whole-foot increments. Example: a 12 x 15 ft room (180 sq ft) with 10% waste gives 180 x 1.10 = 198 sq ft; 198 / 9 = 22.0 square yards; and 198 / 12 = 16.5, rounded up to 17 linear feet off a 12-ft roll. You pay for 17 ft x 12 ft = 204 sq ft = 22.7 sq yd of carpet, but your bill is quoted as 22.7 sq yd.
Which type are you estimating?
Cut pile / plush (bedrooms)
Soft, dense loops are cut at the tip, creating an upright pile that feels luxurious underfoot. Shows footprints and vacuum marks, so it suits low-traffic bedrooms rather than family rooms or stairs. Pairs well with a thick, dense pad (7/16 in, 6 lb density) for the softest feel.
Enter: Enter room length x width; use 10% waste for a rectangular bedroom. Roll width: 12 ft is standard.
Berber / loop pile (family rooms, stairs)
Uncut loops lie flat, giving a durable, dense surface that hides traffic patterns and pet hair. The tighter the loop, the more durable. Ideal for stairs, hallways, and family rooms. Use a firm, thin pad (3/8 in, 8 lb density) -- a thick pad causes Berber to flex and loop snag.
Enter: Add 15% waste for stairs and halls. Note that some Berber comes on 13.5-ft rolls -- confirm with your supplier.
Frieze / twist (casual, hides dirt)
Highly twisted yarns create a textured, casual look that hides footprints and everyday soil well. A good all-around choice for living rooms, home offices, and kids rooms. Mid-range durability between plush and Berber.
Enter: Use 10% waste for rectangular rooms, 15% for rooms with several angles or closets.
Fiber type (nylon / polyester / wool)
Fiber determines durability and price more than style does. Nylon is the most durable and resilient -- the industry standard for high-traffic areas. Polyester is soft, naturally stain-resistant, and less expensive, but mats faster under heavy traffic. Wool is premium: naturally soil-resistant, durable, and eco-friendly, but costs 2-4 x more than synthetic options.
Enter: Quantity is the same regardless of fiber -- enter room dimensions as normal. Budget roughly $2-5/sq yd more for nylon over polyester; wool can run $15+/sq yd.
Carpet pad / cushion (separate purchase)
Pad is sold separately and is required under any broadloom carpet. It adds comfort, extends carpet life by absorbing foot-impact, and improves insulation. Pad is measured in square yards to match the carpet order -- use the same square-yard total. Do NOT add extra waste for pad; the installer trims it to fit.
Enter: Order pad in the same square-yard quantity as the carpet. For most carpet styles, choose 7/16-in thick, 6 lb rebond pad; for Berber, use 3/8-in, 8 lb.
Tips & ways to save
- Order about 10% extra for a rectangular room and 15-20% for stairs, hallways, or patterned carpet -- cuts and seams always produce scrap.
- Seam direction matters: run seams parallel to the longest wall and toward the main light source so seams are less visible from the primary viewing angle.
- A 12-ft roll covers a room up to 12 ft wide in a single piece with no seam. If your room is 13 ft wide, you need either a 13.5-ft roll (if available) or a seamed second strip -- budget extra for labor.
- Keep a labeled remnant from every installation: carpet dye lots change between production runs, so a future patch from the same roll is the only guaranteed match.
- Buy pad at the same time as carpet: installer labor is typically cheaper when pad and carpet go in together, and the right pad adds years to carpet life by cushioning foot-impact stress on the fibers.
Carpet by room size (12-ft roll, 10% waste)
| Room size | Floor area | Square yards | Linear ft (12-ft roll) |
|---|---|---|---|
| 10 × 10 ft | 100 sq ft | 12.2 sq yd | 10 ft |
| 10 × 12 ft | 120 sq ft | 14.7 sq yd | 11 ft |
| 12 × 12 ft | 144 sq ft | 17.6 sq yd | 14 ft |
| 12 × 15 ft | 180 sq ft | 22.0 sq yd | 17 ft |
| 15 × 20 ft | 300 sq ft | 36.7 sq yd | 28 ft |
| 20 × 20 ft | 400 sq ft | 48.9 sq yd | 37 ft |
Square yards = room square footage × waste ÷ 9. Linear feet is how much you pull off a 12-ft-wide roll; you pay for the full roll width, so narrow rooms still waste the leftover strip. Includes 10% waste — add 15–20% for stairs, halls, and patterned carpet.
Frequently asked questions
How much carpet do I need for a room?
How do I convert square feet to square yards of carpet?
Why does carpet come in 12-foot widths?
How many square yards of carpet do I need for a 15 x 20 ft room?
What is the difference between carpet square yards and linear feet?
Should I add waste for carpet stairs?
Sources
Related calculators
Reviewed by the BackyardCalc editorial team. Figures are computed from the formula above and checked against manufacturer yields.