How this calculator works
Carpet comes off a roll of fixed width, so you buy the length you cut, not just the floor area. The calculator lays full-width strips both ways across the room, adds 3″ of trim at each end of every strip, and keeps the layout that uses less carpet. That length times the roll width, rounded up to square yards, is what you pay for.
Pad covers the floor area plus a little for trimming. Tack strip runs around the walls except across doorways, and seam tape covers every seam.
strips = room width across the roll ÷ roll width, rounded up
carpet = strips × (strip length + 6″) × roll width ÷ 9, in sq yd
pad = length × width × 1.05 ÷ 9, in sq yd
tack strip = (perimeter − 3′ per doorway) ÷ 4′, rounded upWorked example
A 15′ × 13′ bedroom is too wide for one 12′ strip either way. Running the strips along the 13′ side takes 2 strips of 13′ 6″, or 27 ft of roll, which is 324 sq ft or 36 sq yd of carpet with one seam. The 195 sq ft floor takes 23 sq yd of pad with 5% for trimming, and 53 ft of wall takes 14 pieces of tack strip.
Tips before you buy
- A room up to 12 feet wide in one direction can usually be carpeted from a single strip with no seam. If yours is a few inches over, ask about 13′6″ or 15′ rolls.
- Seams should run toward the main light source and away from heavy traffic paths, where they show less.
- All strips must run with the pile in the same direction, so fill pieces cannot simply be turned sideways. That is why carpet waste is higher than the floor area suggests.
- Measure each room separately and into closets to the back wall. Carpet layouts are figured room by room.
Questions
- How do I convert square feet to square yards of carpet?
- Divide square feet by 9. A 12′ × 15′ room is 180 sq ft, or 20 sq yd of floor. The carpet you buy is usually more, because it is cut from a roll of fixed width with trim at each end.
- Why is the carpet amount more than my floor area?
- Carpet comes in fixed roll widths, usually 12 feet. If the room is 13 feet wide, you need a second strip and most of it becomes offcut. Installers also add a few inches at each end so the carpet can be trimmed tight to the wall.
- Do I need carpet pad?
- Almost always. Pad makes carpet more comfortable, quieter and longer lasting, and many carpet warranties require a pad that meets a minimum thickness and density. Check the carpet maker’s pad requirements before choosing one.
- How much tack strip do I need?
- Measure the room perimeter and subtract the doorways, since tack strip does not cross them. Tack strip is commonly sold in 4-foot pieces, so divide by 4 and round up. Doorways get a transition strip instead.