How Much Carpet Do I Need for a 12x12 Room
A 12 by 12 bedroom measures 144 square feet. Carpet is sold by the square yard, so the room is 16 square yards, and a store that knows the trade will write up 17. What gets billed is the rectangle cut off the roll.
Why carpet is still sold by the square yard
Carpet is the last flooring category quoted in square yards, a habit carried over from the woven goods trade. One square yard is nine square feet, so 144 divided by 9 is 16. Every line on the invoice will be in yards, pad included. Face weight separates the grades: 25 to 30 oz builder, 40 oz mid-grade, 45 oz and up for a bedroom carpet meant to last 15 years.
The cut piece is what you pay for, not the floor
Carpet ships in 12 ft and 15 ft rolls and is billed on the rectangle taken off the roll. An installer measures wall to wall and adds about 3 inches per dimension for trimming at the baseboard and stretching. A finished room at 11 ft 9 in square cuts at 12 ft by 12.5 ft, which is 150 sq ft or 16.7 sq yd.
What the room costs by grade
These totals cover the 144 sq ft floor. Pad, tack strip and labor are inside the installed rate. National bands, 2026 pricing.
| Grade | Face weight | Material per sq yd | Installed per sq ft | Room total |
|---|---|---|---|---|
| Builder, polyester | 25 - 30 oz | $9 - $18 | $2.50 - $4.00 | $360 - $580 |
| Mid-grade nylon | 40 oz | $18 - $32 | $4.00 - $7.00 | $580 - $1,010 |
| Premium nylon or wool blend | 45 oz and up | $32 - $54 | $7.00 - $12.00 | $1,010 - $1,730 |
Two lines sit outside those totals: removing and disposing of old carpet at $0.50 to $1.00 per sq ft, and a transition strip at $25 to $60.
Padding is not the place to save
Pad is sold by the yard in 6 ft rolls. The 8 lb rebond at 7/16 in is standard for stretch-in carpet over a wood subfloor. Thicker is not better: a 1/2 in pad under loop pile lets the backing flex and the loop opens at the seam, which is why tight loop goods spec 6 lb at 1/4 to 3/8 in. At $0.60 to $1.20 per sq ft, budget $90 to $175 here and do not trade it down.
When the room is wider than the roll
A nominal 12 by 12 room framed with 2x4 walls and half-inch drywall finishes at roughly 11 ft 9 in clear, so 12 ft goods cover it with something to trim. Measure the finished room, never the plan. At 12 ft 2 in the roll no longer reaches and the job moves to 15 ft goods, billed at 21 sq yd with a 3 ft strip you pay for and throw away.
Pile style settles it. A seam in tight loop shows as a line and a change in pile direction, so the 15 ft roll earns its premium. Cut pile hides a seam well enough that 12 ft goods plus a seamed strip is often cheaper.
Add the closet floor while you are at it. A 2 ft by 6 ft reach-in takes 12 sq ft, or 1.33 sq yd, and an L-shaped bedroom splits into two rectangles measured to the inside corners.
The subfloor check before you order
Carpet forgives a floor slightly out of level. It does not forgive one that moves. Look for a soft spot or a ridge at a plywood seam; both telegraph through pad inside a year. A floor that bounces under a heel is a joist question, and the Floor Joist Calculator will show whether span and deflection stay inside L/360. Over a slab, the pad needs a vapor-retardant backing.
Compare the quote line by line
Ask for five numbers: carpet by the yard with the roll width, pad by the yard with its weight, labor, removal, and transitions. A quote in square feet with no roll width cannot be compared to one in yards with it.
For a bedroom with bare feet and no pets, 40 oz nylon over 8 lb rebond is the balance point at about $800 here. The trade-off is honest: a crush path shows in front of the closet by year six, and a wool blend at twice the price will not. If the room becomes a home office, price the hard surface first with the Hardwood Flooring Calculator.