Carpet Calculator
| Room | Sq ft | Sq yd raw | Order (+10%) |
|---|---|---|---|
| Bedroom 12 x 12 | 144 | 16.0 | 17.6 yd |
| Living room 15 x 20 | 300 | 33.3 | 36.7 yd |
| Bedroom 11 x 13 | 143 | 15.9 | 17.5 yd |
| Great room 20 x 24 | 480 | 53.3 | 58.7 yd |
Carpet is sold by the square yard but installed off a 12-foot roll, and that mismatch is the whole estimation game. The math is easy - length times width divided by 9 is square yards - but the roll width decides how the pieces lay out: a 10-foot-wide room takes one 12-foot cut with two feet trimmed off; a 14-foot room needs a full-width piece plus a filler strip, with a seam. Rooms wider than the roll pay for material the trash takes away, and the standard 10 percent waste factor is really a seam-and-cut allowance.
The padding is a second order hiding under the first: cushion runs the same square yards as the carpet, priced separately, and it is not optional - padding carries the warranty. Most residential pad is bonded foam or rebound rated by thickness (7/16 inch is the common sweet spot) and weight in ounces; the carpet will outlive cheap pad, so the square-yard count matters twice, once for the face fiber and once for what is under it.
How to use
- Measure the room at its longest and widest points, including closets and bay windows if they get carpet.
- Read the square yards, then add the 10 percent order factor for seams, pattern matching and cuts around closets.
- Order padding in the same square yards - 7/16-inch bonded foam is the standard residential spec.
Frequently asked questions
How many square yards of carpet for a 12x12 room?
144 square feet divided by 9 is 16 square yards, and at the standard 10 percent factor you order about 17.6 - call it 18 square yards. A 12-foot roll cuts it in one piece with nothing seamed, which is why bedrooms are the cheap jobs: the roll width swallows the room.
Why is carpet sold by the square yard but installed off 12-foot rolls?
The yard price is the accounting unit; the roll width is the physical constraint. Every piece comes off a 12-foot-wide roll, so a 15-foot-wide room is a 12-foot field plus a 3-foot strip seamed in - you pay for roughly rectangle-by-roll-width, not the neat square yards on the sticker. Fewer seams beats saving yards, which is why installers prefer turning the roll to run the long way.
How much extra carpet should I order?
10 percent is the working rule for simple rooms, 15 to 20 percent with stairs, pattern repeats or several closets. Unopened rolls are usually returnable, but cut pieces are not - the waste factor buys seam slack and future patch stock, not padding of the estimate.
How much is carpet per square yard?
Builder-grade carpet runs roughly $20 to $35 a square yard and mid-grade $30 to $50, with wool and premium synthetics well past that; padding adds $5 to $12 a yard. A 20-square-yard living room lands between $500 and $1,200 installed depending on grade - always quote installed per yard, because padding, tack strips and labor hide under a fiber-only price.
Do I need new padding under new carpet?
Yes, and most warranties require it. Padding carries the bounce, muffles sound and takes the wear the face fiber would otherwise - old pad is compressed, dust-loaded and sometimes damp-stained, and reusing it shows through the new carpet within a year. Order it in the same square yards as the carpet; 7/16-inch bonded foam at 6 to 8 pounds is the residential baseline.
How do I measure a room with closets for carpet?
Treat the room plus closets as one rectangle at the widest and longest points - the carpet is cut around the closet openings, not the footprint, so material must cover the bounding box. Bay windows and angled walls add waste; measure each bump-out separately and let the 10 percent factor swallow small ones.