Carpet Square Footage Calculator

Carpet has been sold by the square yard for decades, even though most American flooring uses square feet. One square yard equals 9 square feet, so a 200 sq ft room is about 22.2 sq yd.

When comparing prices, always convert. Carpet at $4/sq yd is much cheaper than carpet at $4/sq ft — about 4.5 times cheaper, in fact.

Carpet typically comes in 12 ft and 15 ft widths. If your room is 13 ft wide, you'll need a 15 ft roll and waste 2 ft of width across the room — or use seams.

A skilled installer can hide seams in low-traffic areas, but seams will always be slightly visible on cut-pile carpets. Plan your room dimensions and roll choice carefully.

US carpet comes almost exclusively in 12-foot rolls, with 15-foot wide and 13.5-foot wide rolls available from premium manufacturers. Roll width is the single most important factor in determining whether your installation will have seams — and where.

If your room's shorter dimension is 12 feet or less, you can usually do a seamless install with a standard 12-foot roll. If it's between 12 and 15 feet, you'll either need a wide-roll carpet or accept a seam. Over 15 feet on the short side, seams are unavoidable.

Worked example: a 14 × 18 ft master bedroom (252 sq ft = 28 sq yd). Option A — 15-ft roll: 15 × 18 = 270 sq ft, no seam, 18 sq ft waste, order 30 sq yd. Option B — 12-ft roll: 12 × 18 main piece + 2 × 18 seam strip = 252 sq ft exactly, plus 10% waste = 31 sq yd, with one seam parallel to the long wall. Option A is cleaner but limits color selection.

Stair carpet calculation is fundamentally different from room carpet because each step has both a tread and a riser plus a small return at the nosing. The pile direction also has to run consistently down all stairs, which forces wasteful cuts.

Standard formula per step: width × (tread depth + riser height + 1.5 in for nosing wrap). For an average 30-inch wide stair with 11-inch tread and 7-inch riser: 30 × 19.5 = 585 sq in per step = 4.06 sq ft. A 13-step staircase: 13 × 4.06 = 52.8 sq ft = 5.87 sq yd.

Always add 20% waste for stairs (not the standard 10%) because of pile direction and the small cuts required at landings and turns. The 13-step example becomes 7 sq yd of carpet ordered.

Carpet pad is sold separately, in the same square yardage as your carpet. Pad density and thickness are spec'd in two numbers: weight (lbs per cubic foot) and thickness (inches). Higher density extends carpet life dramatically, often by 50% or more.

Common pad types: 6-pound rebond ($0.40-0.60/sq ft) is the cheap standard; 8-pound rebond ($0.60-0.80/sq ft) is recommended for most homes; memory foam pad ($1.20-2.00/sq ft) feels luxurious but compresses faster. Berber and looped carpets need a dense, thin pad (1/4-3/8 inch); plush carpets can use thicker pads up to 7/16 inch.

Most manufacturer warranties require minimum pad specs — buying cheap pad can void a $3,000 carpet warranty.