Carpet is sold by the square yard, but you will measure the room in feet. The first job is to get the conversion right, because the showroom quotes in yards and your tape is in feet. After that, plan the roll direction, because carpet comes on a fixed 12 ft width and that width wastes material in ways square footage alone hides.
Measure the room in feet
Pull the furniture back and measure along the longest wall and the shortest wall, in feet. Measure into closets and write those as separate small rectangles, because the installer will cut them from offcuts. Note door swings, because the carpet has to run under the door to meet the hallway.
Convert feet to yards
One square yard is 9 square feet. A 12 ft by 10 ft room is 120 sq ft, which is about 13.3 square yards before waste. The showroom will price by that yard number, so doing the conversion up front keeps the quote honest.
Plan the 12 ft roll
Carpet rolls come 12 ft wide. If the room is 11 ft wide, the whole room fits in one strip with a foot to spare. If the room is 14 ft wide, the installer lays one 12 ft strip and a 2 ft strip cut from another roll, and the leftover edge of that second strip becomes scrap. That scrap is why square footage undercounts real carpet needs.
Budget the waste
Add 10% on top of the converted square yards. That buffer covers the seam strip around a wider room, cuts at doorways, and the odd corner that does not line up. For a room with closets, angles, or stairs, push the buffer higher rather than lower.
What the calculator does not include
Pad under the carpet, tack strips, and door thresholds are quoted separately. The number you order is the face carpet only. Keep a remnant from the same roll, because a future stain patch will not match a new dye lot.
Stairs and patterned carpet
Stairs are quoted by the step, not by square yard, so measure the rise and run of each tread and tell the installer. If the carpet has a pattern, the repeat width decides how much scrap you lose at every seam, and you should bump the waste to 15% rather than 10%. Solid colors and low-pile berbers lay out the most efficiently.
Worked example
A 12 ft by 10 ft room, converted to 13.3 square yards, plus 10% waste, lands near 15 square yards. That is the number to hand the showroom.
Carpet Calculator
One square yard is 9 square feet, carpet rolls ship 12 ft wide, and a 10% waste buffer covers seams and cuts at the door.
How to use
- Measure the room length and width in feet
- Plan which way the 12 ft roll will run
- Convert square feet to square yards by dividing by 9
- Add the 10% waste buffer
- Read the square yard total to order
Supported formats and limits
- One square yard equals 9 square feet
- Standard carpet rolls are 12 ft wide
- Rooms wider than 12 ft need a seam, which the waste buffer covers
Examples
A 12 ft by 10 ft room at 10% waste lands near 15 square yards.Common errors
- Room length and width must be positive
- Waste should sit between 0 and 30 percent
Privacy and browser support
All calculations run locally in your browser. No room measurements are uploaded.
FAQ
How do I turn square feet into square yards?
Divide the square footage by 9. A 120 sq ft room is about 13.3 square yards before waste, and close to 15 with the 10% buffer.
How wide is a carpet roll?
Most residential carpet ships 12 ft wide. Some commercial grades run 15 ft. The roll width decides where seams fall.
Why does a wider room waste more?
If a room is 13 ft wide, the 12 ft roll leaves a 1 ft strip cut from another length, and the offcut cannot always be reused. The 10% buffer absorbs that loss.
Where should seams fall?
Run seams along the traffic path, not across it, and keep them out of doorways. A good installer lays the roll so one big piece covers most of the room.
How much extra should I order?
Ten percent is the baseline. Odd shapes, closets, and stairs push it higher. Never skimp, because dye lots change between orders.
Do I pad and tack strip too?
Yes. The calculator covers carpet face goods only. Pad is quoted separately, usually sold by the square yard as well.