Estimate carpet for a room — in square feet and square yards, the way carpet is sold — with a waste factor.
sq yd = area × (1 + waste) ÷ 9
Carpet is often priced by the square yard. Add waste to the room area, then divide by 9 to convert square feet to square yards.
Rooms wider than the carpet roll (usually 12 ft) need seams — add extra for matching.
A 12 x 15 ft room is 180 square feet, or 20 square yards — carpet is traditionally priced per square yard. Add 10% waste and you'd buy about 22 square yards.
Carpet comes on rolls that are usually 12 ft wide. Because this room is exactly 12 ft in one direction, you can run the carpet without a seam. A room wider than 12 ft needs a seam, which adds waste for pattern matching and a strip for the seam itself — plan the seam away from high-traffic and sight lines.
One square yard is 9 square feet. Carpet rolls are typically 12 ft wide, which affects seam placement and waste.
About 14.7 square yards including 10% waste.