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Carpet Calculator

Walking into a flooring store with the wrong yard count is how you end up paying for carpet you don't need or making a second trip when the installer runs short. Carpet is sold by the square yard, comes in 12-foot (sometimes 15-foot) rolls, and every cut, seam, and pattern repeat eats into yield. This calculator gives you a clean square-yard total — plus the matching pad order — with a tunable waste factor. Plain residential carpet runs 10% waste; patterned carpet runs 15-20%. Add an optional price per square yard and get your material cost estimate too.

How carpet is sold (and why waste matters)

Carpet comes in 12-foot wide rolls (most US residential) or 15-foot wide rolls (less common, mostly for big rooms). Your room dictates how the carpet has to be cut to lay flat without seams running across high-traffic areas. A 14x12 room fits perfectly across a 12-ft roll — just one length of 14 feet, no seam, no waste. A 14x14 room needs a small filler strip with a seam, adding waste.

Math: square feet × (1 + waste %) ÷ 9 = square yards. Waste varies by:

  • 10% — plain solid color carpet, simple rectangular rooms
  • 15% — plain carpet with multiple rooms or irregular spaces
  • 15-20% — patterned carpet that requires pattern matching at seams
  • 20%+ — large patterns, stairs, complex layouts

Worked example: a 14 ft x 12 ft room = 168 sq ft. At 10% waste = 184.8 sq ft = 20.5 square yards. Order 21 yards of carpet and 21 yards of pad. At $25/yd carpet + $4/yd pad = $609 in materials, before install.

Pad selection

Pad isn't optional — carpet without pad wears out 30-50% faster, feels harsh underfoot, and voids most carpet warranties. Standard residential pad:

  • 7/16" 6-lb rebond — the residential workhorse. Recycled foam, soft underfoot, $0.50-1.00/sq ft.
  • 3/8" 8-lb rebond — firmer, better for high-traffic areas and Berber carpet. ~$1.00-1.50/sq ft.
  • 1/2" memory foam — premium soft pad for bedrooms. ~$1.50-2.50/sq ft. Don't use on stairs.
  • 1/4" rubber slab — for commercial / contract carpet, very thin and firm.

Pad thicker than 1/2" actually accelerates carpet wear because the carpet flexes too much underfoot and breaks down faster. Don't over-cushion.

How to use this calculator

  1. Length and width: measure the longest and widest points of the room in feet. For L-shaped or irregular rooms, break into rectangles and run each.
  2. Waste percent: 10 for simple rooms, 15-20 for patterned carpet or complex layouts.
  3. Carpet price per sq yd (optional): big-box carpet runs $15-35/sq yd, mid-grade $35-60, premium $60-100+. Add another $4-8/sq yd for installation.
  4. Output: square yards needed (which equals the pad order), square feet for double-check, and estimated cost.

Common scenarios

14x12 bedroom, plain plush carpet, 10% waste. 184 sq ft = 21 sq yd. Carpet at $35/yd + pad at $5/yd = $840 in materials. Install runs $5-8/yd installed = total around $1,000.

3 bedrooms + hallway, 480 total sq ft, mid-grade Berber, 15% waste. 552 sq ft = 61 sq yd. Carpet at $40/yd + 8-lb pad at $6/yd + install at $6/yd = $3,170 turnkey for the upstairs.

Stairs (typical 13 risers + treads), pattern carpet. Each step takes about 1 sq yd of carpet with waterfall install method (vs about 0.7 sq yd with cap-and-band install). 13 steps × 1 = 13 sq yd at 20% waste = 16 sq yd ordered. Stair install is labor-intensive — plan $15-25 per stair installed on top of material.

FAQ

Why is carpet sold by the square yard instead of square foot? +
Historical convention from when carpet came on textile looms in fixed-width rolls measured in yards. Conversion: 1 sq yd = 9 sq ft. Most stores price per sq yd; some big-box stores now price per sq ft. Always confirm which unit you're being quoted before signing.
Plush, Berber, or frieze — what's the difference? +
Plush is the traditional cut-pile, soft, shows footprints and vacuum marks. Berber is loop pile, durable, hides traffic patterns, can snag on pet claws. Frieze is twisted cut-pile, casual look, hides wear well, sheds less. For pets/kids: Berber or frieze. For formal bedrooms: plush. For high-traffic: frieze with stain-resistant fiber.
Nylon, polyester, or wool? +
Nylon: the durability champion, best for high-traffic, accepts stain treatment well. Polyester (PET, triexta): cheaper than nylon, softer underfoot, inherently stain-resistant, slightly less durable. Wool: premium natural fiber, beautiful but expensive ($100+/yd) and needs careful cleaning. For 90% of homes, mid-grade nylon is the right answer.
Should I install carpet myself? +
Stretch-in carpet (the standard residential method) requires a knee kicker, power stretcher, seaming iron, and stair tools — plus knowledge of how to seam and stretch without buckles. Installation is hard physical work and harder to do well than YouTube makes it look. For one room: maybe, with rental tools. For a whole house: hire it out. Bad install ruins good carpet.
How long does carpet last? +
Builder-grade nylon: 5-10 years. Mid-grade nylon or polyester: 10-15 years. Premium nylon: 15-25 years. Wool: 20-30 years. Big factors that shorten life: pets (claws and accidents), no shoes-off rule (dirt is abrasive), no regular vacuuming, no professional cleaning every 12-18 months.
Can I install carpet over existing carpet? +
No — it'll trap moisture and the layered cushion crushes carpet faster. Always tear out the old carpet and pad, vacuum the subfloor, and re-tack-strip the perimeter. New tack strips (1/4" away from the wall, sharp pins pointing toward the wall) go down before the new pad.
What about transitions to other floors? +
Carpet-to-hard-floor transitions use a metal Z-bar or carpet transition strip nailed into the subfloor at the doorway. Tucks the carpet edge under and prevents fraying. Sold by the linear foot at flooring suppliers, ~$10-20 per doorway transition.
Can carpet be installed on stairs by myself? +
The two methods are waterfall (carpet drapes over the nose) and cap-and-band (carpet wraps the nose with a fold). Cap-and-band looks better and is the pro standard but requires hand-stretching each tread and riser separately. Waterfall is DIY-friendly but the carpet wears faster at the stair nose. Either way it's a slow careful job — a 13-step staircase takes 4-6 hours.