How do I convert square feet to square yards for carpet?

Divide square feet by 9, because a square yard is 3 ft by 3 ft. A 12 by 15 ft room is 180 square feet, or 20 square yards. Carpet is priced per square yard, so multiply square yards by the price per yard, but remember you'll buy more than the floor area because of roll width.

How wide is a roll of carpet?

Most broadloom carpet is 12 ft wide. Some styles also come in 13 ft 6 in or 15 ft widths. The roll width matters because rooms wider than the roll need more than one strip and a seam, and the leftover width of each strip is often waste.

Why do I need more carpet than my room's square footage?

Carpet comes off a roll of fixed width, so you buy full-width strips. A 15 ft wide room on a 12 ft roll needs two strips, which leaves 9 ft of the second strip's width unused. Installers also add a few inches at each end for trimming. That can add 30% or more in wide rooms.

How much carpet pad do I need?

Pad covers the floor area, not the carpet bought, so take the room's square feet, divide by 9 and round up. Pad comes in rolls and is butted together at the seams, so it has far less waste than the carpet itself. For 518 square feet of rooms, that's 58 square yards of pad.

Where should carpet seams go?

Away from doorways, main walking paths and the middle of the room where possible, and running the same direction as the main light source so they show less. All strips must run with the pile in the same direction. An installer will plan seam placement, which can change the cut list.

Free calculator

Carpet Calculator: Square Yards and Roll Length

Free carpet calculator: square feet, square yards and roll length for 12 ft and 15 ft rolls, with seams and waste.

RoomLengthWidth

Feet, or feet and inches: 12, 12.5, 12' 6".

Roll width

Price per sq yd (optional)

Carpet is priced by the square yard (9 sq ft).

Result

Carpet to buy

71.3sq yd

53' 6" off a 12 ft roll

Floor area: 518 sq ft
Floor area in sq yd: 57.6 sq yd
Strip offcuts and trim: 13.8 sq yd
Seams: 1
Pad: 58 sq yd

Each room is cut from the roll on its own, running strips whichever way uses less carpet, with 3 in extra at each end for trimming. Your installer may fit offcuts into closets and reduce the total.

How it's calculated

Square yards = length × width ÷ 9, but you buy whole strips off the roll: strips × (room length + trim) × roll width. A 15 × 18 ft room is 30 sq yd of floor. On a 12 ft roll it takes two 15 ft 6 in strips, so you buy 41.3 sq yd with one seam; on a 15 ft roll, one strip of 30.8 sq yd.

How to use the carpet calculator

Enter each room's length and width in feet or feet and inches, then choose the roll width your carpet comes in. For every room the calculator tries running the strips both ways and keeps the one that uses less carpet, adds 3 in at each end for trimming, and adds up the square yards you'll pay for. Pad is figured from the floor area. Add a price per square yard to see the cost.

Floor area vs. carpet bought

Square yards of floor, and square yards bought on each roll width, with seams:

Room	Floor	12 ft roll	15 ft roll
10 × 10 ft	11.1 sq yd	14.0 sq yd, no seam	17.5 sq yd, no seam
12 × 14 ft	18.7 sq yd	19.3 sq yd, no seam	20.8 sq yd, no seam
13 × 15 ft	21.7 sq yd	36.0 sq yd, 1 seam	22.5 sq yd, no seam
15 × 18 ft	30.0 sq yd	41.3 sq yd, 1 seam	30.8 sq yd, no seam
16 × 20 ft	35.6 sq yd	44.0 sq yd, 1 seam	55.0 sq yd, 1 seam

A room just wider than the roll is the expensive case: a 13 ft room on a 12 ft roll needs a second strip for a 1 ft sliver. When a room is a little over 12 ft wide, ask whether the carpet comes in a wider roll.

How carpet is sold

By the square yard. Prices are per square yard (9 sq ft). Some stores show a per-square-foot price; multiply it by 9 to compare.
Off a roll. Most broadloom is 12 ft wide; 13 ft 6 in and 15 ft widths also exist. You pay for the full width of every strip.
Pile direction. Strips can't be turned sideways to fill a gap, because the pile must run the same way across the room. That's why offcuts often can't be reused in the same room.
Pad separately. Pad is priced by the square yard too, and covers only the floor area.

Stairs, closets and halls

Closets and halls are narrow, so they're good places for offcuts from a big room, if the pile direction works. This calculator cuts each room separately, which is a safe upper bound; an installer's cut plan may come in lower. Stairs are estimated per step by installers and aren't included here.

If you have a floor plan, FloorFigures gives each room's size from it, free, so you can paste exact dimensions here. For other floor types, see the flooring calculator.

Updated October 12, 2026 · FloorFigures

Questions

How do I convert square feet to square yards for carpet?: Divide square feet by 9, because a square yard is 3 ft by 3 ft. A 12 by 15 ft room is 180 square feet, or 20 square yards. Carpet is priced per square yard, so multiply square yards by the price per yard, but remember you'll buy more than the floor area because of roll width.
How wide is a roll of carpet?: Most broadloom carpet is 12 ft wide. Some styles also come in 13 ft 6 in or 15 ft widths. The roll width matters because rooms wider than the roll need more than one strip and a seam, and the leftover width of each strip is often waste.
Why do I need more carpet than my room's square footage?: Carpet comes off a roll of fixed width, so you buy full-width strips. A 15 ft wide room on a 12 ft roll needs two strips, which leaves 9 ft of the second strip's width unused. Installers also add a few inches at each end for trimming. That can add 30% or more in wide rooms.
How much carpet pad do I need?: Pad covers the floor area, not the carpet bought, so take the room's square feet, divide by 9 and round up. Pad comes in rolls and is butted together at the seams, so it has far less waste than the carpet itself. For 518 square feet of rooms, that's 58 square yards of pad.
Where should carpet seams go?: Away from doorways, main walking paths and the middle of the room where possible, and running the same direction as the main light source so they show less. All strips must run with the pile in the same direction. An installer will plan seam placement, which can change the cut list.

Skip the typing. Measure the plan.

Open the floor plan in FloorFigures and every room is measured for you, with the same math per room. Try it free on a sample plan; nothing is uploaded.