How carpet is measured and sold
Carpet is cut from wide rolls and priced by the square yard. Because the roll has a fixed width, the amount you buy depends on how many strips it takes to cover the room, not just the room's area. The calculator checks both directions you could run the carpet and picks the one that uses less.
Strips = room width ÷ roll width, rounded up
Carpet to buy = strips × roll width × (room length + trim) ÷ 9
Example: a 15 × 14 ft room is 210 sq ft, or 23.3 sq yd. Both sides are wider than a 12 ft roll, so it takes 2 strips. Running them 14.5 ft long (including 3 inches of trim at each end) uses 2 × 12 × 14.5 = 348 sq ft, or 38.7 sq yd, with one seam. A 15 ft roll covers the room in a single 14.5 ft strip: 15 × 14.5 = 217.5 sq ft, or 24.2 sq yd, and no seam.
Room area in square yards
| Room size | Square feet | Square yards |
|---|---|---|
| 10 × 10 ft | 100 | 11.1 |
| 10 × 12 ft | 120 | 13.3 |
| 12 × 12 ft | 144 | 16.0 |
| 12 × 15 ft | 180 | 20.0 |
| 14 × 16 ft | 224 | 24.9 |
| 15 × 20 ft | 300 | 33.3 |
Tips for buying carpet
- Measure each room at its widest and longest points, including closets and doorways that will be carpeted.
- Choosing a wider roll can eliminate seams in rooms up to 15 feet wide. Seams are where carpet wears and shows first.
- Patterned carpet needs extra to match the pattern across seams. Add the pattern repeat to each strip's length.
- Ask whether quotes include pad, installation, removal of old carpet and moving furniture.
Frequently asked questions
How do I convert square feet to square yards for carpet?
Divide square feet by 9, because one square yard is 3 feet by 3 feet. A 12 × 15 ft room is 180 square feet, or 20 square yards.
Why do I need more carpet than my room's area?
Carpet comes off rolls that are usually 12 or 15 feet wide. If your room is wider than the roll, you need extra strips that are seamed in, and the leftover width is often wasted. Seams, pattern matching and trimming at the walls add more.
What carpet roll widths are available?
12 feet is the most common width in the US, with 15 feet available in many styles and 13 foot 2 inch widths for some. A wider roll can let you carpet a room without any seams.
How much carpet pad do I need?
Pad is needed for the room's actual floor area, plus a little for trimming. It comes in rolls and doesn't need to match the carpet's roll layout, so it wastes less.
How much carpet do I need for stairs?
Each standard stair needs a piece about 3 feet wide and roughly 1.5 to 2 feet long to cover the tread and riser, so plan on about 0.5 to 0.75 square yards per step, more for open-sided or wraparound stairs.