Carpet Calculator
Enter the size of your room and the width of the carpet roll to see how many square yards to buy and how much roll length to cut. Carpet is sold in wide rolls, so the layout matters.
How to use this carpet calculator
- Measure the longest length and widest width of the room. For an L-shaped room, calculate each part and add them.
- Enter the width of the carpet roll you plan to buy. Many rolls are 12 ft wide, but ask the store.
- Keep the waste allowance or change it. Patterned carpet and rooms with many corners need more.
- Add a price per square yard if you want a cost estimate, then press Calculate.
- Use Copy result or Export CSV to take the numbers to the store.
How to calculate how much carpet you need
The calculator shows two views: the area you need and the roll length you would actually cut.
- Area = room length x room width (sq ft)
- Square yards = area / 9, then x (1 + waste % / 100)
- Roll length option 1 = strips needed across the width (width / roll width, rounded up) x room length
- Roll length option 2 = strips needed across the length x room width
- Roll carpet bought = shorter option x roll width / 9 square yards
Worked example
A room is 15 ft by 12 ft, so the area is 180 sq ft, or 20 sq yd. With 10% waste you need 22 sq yd. The roll is 12 ft wide. Running the carpet along the 15 ft length takes one strip of 15 linear ft, which is 20 sq yd of roll. Running it the other way would take two strips of 12 ft, or 24 linear ft, so the first layout is better. At $30 per square yard, 22 sq yd costs $660.00.
Assumptions & limits
- The room is a simple rectangle. Closets, stairs and odd shapes need to be added separately.
- Roll widths are not standardized. The 12 ft default is an editable placeholder, so check the width of the carpet you choose.
- The roll length does not plan seams, pile direction or pattern matching. A store can give an exact layout.
- The cost uses your price per square yard on the area with waste. Pad, tack strip, labor and removal are not included.
- Carpet is cut from a continuous roll, so you usually pay for the whole width you buy.
Frequently asked questions
How do I calculate how much carpet I need?
Multiply the room length by the width in feet, divide by 9 to get square yards, and add waste. A 15 ft by 12 ft room is 20 square yards before waste.
How many square feet are in a square yard?
There are 9 square feet in a square yard. Divide square feet by 9 to convert.
How wide is a roll of carpet?
Widths vary. 12 ft is common, and 15 ft rolls exist, but you should confirm with the supplier and enter that width.
How much waste should I allow for carpet?
Ten percent is a common starting point. Patterns, stairs and rooms with many corners need more.
Why is the roll length different from the area?
Carpet is cut from a wide roll, so part of the width may be trimmed away. The roll length shows the carpet you pay for in a simple layout.
Does the cost include padding?
No. The estimate covers carpet only. Padding, tack strip, installation and removal are separate.
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Last updated: November 2026