Roll and layout
Type feet and inches like 12'6" or just 12.5. Add one area for each room, or pick Stairs. Everything is saved on this device.
About the carpet calculator
This free carpet calculator tells you how much carpet to buy. Carpet is not sold by the floor area. It comes off a roll 12 ft or 15 ft wide (4 m or 5 m in Europe), and the shop cuts a length for you. So a room that is 13 ft wide needs two strips from a 12 ft roll, and a lot of carpet is cut off.
Enter your rooms and stairs. The calculator lays the strips for each room, adds a little for trimming, and gives the square yards to buy, the length off the roll, the seams and the waste. Add padding and prices to see the full cost.
Features
- Roll width — 12 ft or 15 ft, 4 m or 5 m, or your own width
- Real roll layout — strips, seams and the length off the roll for each room, not just the floor area
- Fewer seams or less carpet — lay the strips the long way, or the way that wastes less
- Stairs — one piece per step, with the nosing, cut so the pile runs down the stairs
- Waste in percent — see how much of the carpet is cut off
- Padding and cost — padding area, carpet, padding and installation prices per square yard
- Feet or metres — square yards or square metres
- Saved on this device — the list is still there in the carpet shop
How carpet is cut from the roll
Think of the roll as a long strip 12 ft wide. For each room the shop cuts one or more pieces off the end:
- The strips run along the longer side of the room, so there are as few seams as possible.
- The number of strips is the shorter side ÷ the roll width, rounded up. A room up to 12 ft wide needs one strip from a 12 ft roll. A room 13 ft wide needs two.
- Each strip is as long as the room, plus about 6 in (15 cm) for trimming at the walls.
- What you buy is the length off the roll × the roll width. Divide square feet by 9 to get square yards.
This is why the waste can be large. A 20 × 13 ft room needs two strips of 20 ft 6 in from a 12 ft roll, but only one strip from a 15 ft roll. Pick Way with less carpet to let the calculator turn the strips across the room when that is shorter. The seams are then shorter too, but they run across the room.
Pile direction: carpet has a nap, like velvet. Every piece in a room must have the pile running the same way, or the two sides of a seam look like two colours. The calculator never turns one strip against the others.
Worked examples
These numbers come from the calculator with its first settings: a 12 ft roll, 6 in of trim on each strip and 5% extra.
| Room | Layout | Off the roll | To buy | Waste |
|---|---|---|---|---|
| 15 × 12 ft bedroom | 1 strip, no seam | 16.3 ft | 21.7 sq yd | 8% |
| 11 × 10 ft room | 1 strip, no seam | 12.1 ft | 16.1 sq yd | 24% |
| 20 × 13 ft, long way | 2 strips of 20.5 ft, 1 seam 20 ft long | 43.1 ft | 57.4 sq yd | 50% |
| 20 × 13 ft, way with less carpet | 2 strips of 13.5 ft, 1 seam 13 ft long | 28.4 ft | 37.8 sq yd | 24% |
| 20 × 13 ft on a 15 ft roll | 1 strip, no seam | 21.5 ft | 35.9 sq yd | 19% |
| 13 stairs, 3 ft wide | 4 pieces side by side, 4 rows | 6.6 ft | 8.9 sq yd | 29% |
The 15 × 12 ft bedroom: the room is 12 ft wide, so one strip fits. The strip is 15 ft + 6 in = 15.5 ft long. With 5% extra that is 16.3 ft. 16.3 × 12 = 195.3 sq ft, and 195.3 ÷ 9 = 21.7 sq yd. The floor is 180 sq ft, so 8% is cut off or spare.
In metres: a 5 × 3.8 m room on a 4 m roll needs one strip of 5.15 m, which is 21.6 m² with 5% extra. A 6 × 4.5 m room needs two strips from a 4 m roll (51.7 m²) but only one from a 5 m roll (32.3 m²). Always ask which roll widths the shop has.
Carpet on stairs
Each step needs one piece: the tread (where you step), the riser (the front) and about 1.5 in (4 cm) to wrap round the nosing. Pieces are cut side by side across the roll, so the pile runs down the stairs.
For 13 steps 3 ft wide, with a 10 in tread and a 7.5 in riser:
- One piece is 10 + 7.5 + 1.5 = 19 in long
- A 12 ft roll holds 4 pieces side by side, so 13 steps need 4 rows
- 4 × 19 in = 76 in = 6.3 ft, or 6.6 ft with 5% extra — 8.9 sq yd
Stairs with a curve or a landing need a different cut. Ask the installer to measure them.
Padding and the cost
Padding (underlay) goes under the carpet in the rooms and on the treads. The calculator gives its area with the same extra percent. Installers charge per square yard of carpet, so the installation price is applied to the carpet you buy.
For the 15 × 12 ft bedroom, with example prices (check your own):
| Item | Amount | Price | Cost |
|---|---|---|---|
| Carpet | 21.7 sq yd | $25 per sq yd | $542.50 |
| Padding | 21 sq yd | $5 per sq yd | $105.00 |
| Installation | 21.7 sq yd | $8 per sq yd | $173.60 |
| Total | $821.10 |
Frequently asked questions
How much carpet do I need for a 12 × 12 room?
One strip from a 12 ft roll: 12 ft + 6 in trim = 12.5 ft. That is 150 sq ft, or 16.7 sq yd before the extra. The floor is 144 sq ft (16 sq yd), so the trim is the only waste.
How do I convert square feet to square yards of carpet?
Divide by 9. A room of 180 sq ft is 20 sq yd. But buy by the roll layout, not by the floor area: the same room can need 21.7 sq yd.
Why does the shop sell me more carpet than my floor area?
Because carpet comes off a roll of a fixed width. When the room is not exactly as wide as the roll, the rest of the width is cut off. A second strip for a wide room can almost double the waste.
Should I use a 12 ft or a 15 ft roll?
Use the roll that covers the shorter side of the room in one piece. A room up to 12 ft wide fits a 12 ft roll. A room between 12 and 15 ft wide fits a 15 ft roll with no seam and much less waste.
Where should carpet seams go?
Out of doorways and busy paths, and best along the light from the main window, so the seam is harder to see. Keep the pile of both pieces running the same way.
How much extra carpet should I buy?
The roll layout already holds the trim. Add about 5% for mistakes and odd corners. Rooms with many corners, closets or bay windows need more.
Can a shop fit two small rooms into one cut?
Sometimes. A good shop fits closets and small pieces into the left-over width. The calculator cuts each room on its own, so its number can be a little higher than the shop's plan.
Related tools
- Square Footage Calculator — the area of odd-shaped rooms
- Flooring Calculator — boxes of laminate or vinyl plank
- Tile Calculator — tiles for a bathroom or kitchen
- Paint Calculator — paint for the walls of the same room
- Unit Converter — square feet, square yards and square metres
How to use it
- Choose Feet & inches or Metres & cm
- Enter the length and width of the first room. Use Add another room or stairs for more
- For stairs, pick Stairs and enter the width, riser height, tread depth and number of steps
- Pick the roll width the shop sells, and how to lay the strips
- Add a carpet price per square yard (padding and installation prices are in the fold-out)
- Read the square yards, the length off the roll and the seams, then press Copy the list
