How much carpet do I need?
Carpet is sold by the square yard. Multiply each room's length by its width, add extra for seams and trimming, and divide by 9.
Square yards = length (ft) × width (ft) × (1 + waste %) ÷ 9
A 12 × 12 ft bedroom is 144 sq ft, or 16 sq yd. With 10% extra that's 158.4 sq ft, or 17.6 sq yd of carpet and 17.6 sq yd of pad. Tack strip runs around the 48 ft perimeter: 12 pieces of 4 ft.
Carpet calculator cost
With the default prices, $27 per sq yd carpet ($3 per sq ft), $5 per sq yd pad and $9 per sq yd installation, the bedroom comes to:
| Item | Quantity | Cost |
|---|---|---|
| Carpet | 17.6 sq yd | $475 |
| Pad | 17.6 sq yd | $88 |
| Tack strip | 12 pieces | $7 |
| Installation | 17.6 sq yd | $158 |
| Total | $729, about $41 per sq yd |
These are editable defaults, not local quotes. Stores often list carpet per square foot; multiply by 9 for the square yard price. Ask whether the install price covers removing old carpet, moving furniture and stairs, since those are often extra.
Roll width and seams
Carpet comes off rolls that are usually 12 ft wide, and some styles come in 15 ft. If a room is wider than the roll in both directions, it needs a seam. Every piece has to run the same pile direction, so the fill piece is cut from a full-width strip and the rest is waste unless it fits a closet or another room.
A 14 × 16 ft room is wider than a 12 ft roll both ways. Plan on 15–20% extra: at 15%, 224 sq ft becomes 257.6 sq ft, or 28.7 sq yd. The calculator flags rooms like this. For an exact number, ask the store for a seam diagram before you order.
Measuring tips
Measure wall to wall at the widest point and round up to the next half foot. Include closets as their own rooms. Measure into each doorway to the center of the door, where the carpet meets the next floor. For stairs, measure one step from the back of the tread, over the nose, to the bottom of the riser, multiply by the stair width, and add a room for the steps.
Pricing a carpet job
Carpet installers usually price labor per square yard, so the calculator adds installation as its own line at your rate, with no markup. To bill by the hour instead, pick materials only and the job ticket adds a labor line. Switch to contractor mode to set your markup, then send it with the estimate template.
Questions
How many square yards of carpet do I need for a 12 × 12 room?
144 sq ft is 16 sq yd. With 10% extra for trimming, order about 17.6 sq yd.
How do I convert square feet to square yards?
Divide by 9. 100 sq ft is 11.1 sq yd, and 200 sq ft is 22.2 sq yd.
How much extra carpet should I buy?
Typically 10% for rooms narrower than the roll and 15–20% for rooms that need a seam. Patterned carpet can need more to match.
Do I need new pad with new carpet?
Usually yes. Most carpet warranties call for a specific pad thickness and density, so check before reusing old pad.