Carpet calculator: how much carpet do I need?

How much carpet do I need? The math in words

1. Work out the floor area: length times width, both in feet. Add closets and any other part of the room as more rectangles; the square footage calculator covers odd shapes.
2. Add the extra: Flooring America recommends 5% to 10% for waste, seams and pattern matching. The calculator starts at 10%.^[1]
3. Divide by 9 for square yards, because a square yard is 9 square feet.^[2]
4. Divide by the roll width for the length of carpet off the roll. Most carpet is 12 feet wide; some comes 13.5 or 15 feet.^[1][3]

Example: an 11 by 14 foot bedroom. Area: 154 square feet; plus 10% makes 169.4. In square yards: 169.4 ÷ 9 = 18.8. Off a 12 foot roll: 169.4 ÷ 12 = 14.1, so about 15 feet.

How carpet is really cut: the roll decides

Carpet is cut from the roll in full-width pieces. The installation standard for homes, CRI 105, has the carpet cut to a seaming diagram with at least 3 inches along each wall for trimming, seams kept to a minimum and run the length of the room.^[4] So a room that fits inside the roll's width takes one piece: the roll's width by the room's length plus the trim.

The 11 by 14 foot bedroom fits a 12 foot roll: one piece 12 feet by 14 feet 6 inches, which is 174 square feet or 19.3 square yards, close to the calculator's 18.8. A 14 by 16 foot living room is wider than a 12 foot roll, so it needs a seam, or one piece off a 15 foot roll: 15 by 16 feet 6 inches, 247.5 square feet or 27.5 square yards.

Patterned carpet takes more, because the pattern has to line up across each seam.^[4] Raise the extra for a pattern or a room with angled walls.

Square feet to square yards

Carpet is often priced by the square yard and rooms are measured in square feet. A square yard is 9 square feet, so divide square feet by 9; it is also about 0.836 square meters.^[2] The calculator shows square yards for the carpet, and the square footage calculator shows square feet, square meters and square yards for any room.

Example: a 320 square foot living and dining room is 320 ÷ 9 = 35.6 square yards; with 10% extra, 39.1 square yards.

Odd-shaped rooms from one walk

Carpet quotes go wrong in the odd corners: a closet, a bay window, an angled wall by the stairs. PlaceAnew measures them in one walk. Hold an iPhone or iPad with LiDAR (iPhone 12 Pro or a newer Pro model, or an iPad Pro from 2020 or later), walk through the rooms, and the floor plan comes out with every room named and measured, its square footage and the total, worked out from the walls it found, angled ones included. The Measure tool reads any distance on the plan, so the length and width for the roll are right there.

The sizes hold up: in one walk of our own office, the office came out at 195 square feet against 197 on the hand-measured plan.^[5] Scanning, floor plans, 3D, editing, the kitchen designer with prices and exports are free. Send the PDF with the quote and the client sees every room that is priced.

Questions people ask