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Flooring & TileCarpet Calculator — How Much Carpet Do I Need?
Enter the room’s length and width to get the area and the square footage to buy, including a 10% allowance for seams, trimming, and pattern matching.
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How this calculator works
We multiply length × width for the room area and add 10% for seams, trimming, and matching. Carpet often comes on 12-ft-wide rolls, so real waste depends on how your room fits that width — divide the sq ft by 9 for square yards if your store prices that way.
What changes how much you need
- Carpet rolls are usually 12 ft wide; odd room widths can force more waste than 10%.
- Run the pile direction consistently and plan seams away from doorways and high-traffic lines.
- Add for stairs separately — about 1.5 sq ft per stair tread-and-riser.
- Order pad/underlay to the same room area.
Frequently asked questions
How much extra carpet should I buy?
About 10% for most rooms. Add more if the room is wider than the 12-ft roll in an awkward way, or for patterned carpet.
How do I convert square feet to square yards?
Divide square feet by 9. Many carpet stores still price by the square yard.
Do I need extra for stairs?
Yes — budget roughly 1.5 sq ft per step (tread plus riser), plus a little for wrapping the nose.