Carpet Calculator — Square Feet & Square Yards
Carpet in the US is priced per square yard but rooms are measured in square feet. This calculator handles both, plus a 10% waste factor and padding cost.
Last updated:Tip: If you only have the diameter, divide by 2 to get the radius.
L-shape = two rectangles sharing a corner.
Add one row per rectangle and we'll sum them.
Carpet Square Footage to Square Yards
Carpet retailers typically price by the square yard. Convert: 1 sq yd = 9 sq ft. Divide your total sq ft by 9 to get sq yd. The calculator above shows both values side-by-side.
Example: 15 × 20 Living Room
- Area: 15 × 20 = 300 sq ft
- With 10% waste: 330 sq ft
- In square yards: 330 / 9 = 36.67 sq yd → 37 sq yd to order
- At $4.50/sq yd material: $166.50; at $7/sq yd installed: $259
Carpet Waste Factors
| Layout | Waste | Why |
|---|---|---|
| Single room, one seam | 10% | Standard cut waste. |
| Pattern-matched carpet | 15% | Extra for aligning pattern across seams. |
| Multiple rooms, one roll | 12% | Need to plan direction. |
| Stairs (per stair) | n/a | Use 2 sq ft per stair tread + 1 sq ft per riser. |
Don't Forget the Carpet Pad
Padding is priced per sq ft and sold in rolls of the same size as your carpet order. Plan to buy the same square footage of padding as carpet. Common pad types:
- Rebond (8-lb): $0.40–$0.60 / sq ft — standard residential.
- Memory foam: $0.80–$1.50 / sq ft — best for plush carpet.
- Rubber: $0.80–$1.20 / sq ft — best for basements.
Seam Planning for Carpet Rolls
Standard US carpet comes in 12-foot-wide rolls (some styles are 13 or 15 ft). To minimize visible seams:
- Run the 12 ft width across the shorter dimension of the room.
- Hide seams along main walk paths, not across them, so foot traffic wears the seam evenly.
- Align pile direction the same way on every piece — otherwise the seam will catch light differently.
- Add 1% extra on top of the 10% waste factor when the room is wider than the roll and needs a seam.
Carpet for Stairs
Stairs need a little extra math. Budget 2.5 sq ft per step for carpet and the same for padding. For a typical 13-stair run:
- 13 steps × 2.5 sq ft = 32.5 sq ft
- With 10% waste: 36 sq ft
- In square yards: 36 ÷ 9 = 4 sq yd
Add the stair total to the main floor total before ordering — the installer wants one continuous piece whenever possible.
Carpet Costs by Fiber (2026)
| Fiber | Cost (USD / sq yd) | Notes |
|---|---|---|
| Olefin / polypropylene | $10 – $18 | Budget, stain resistant, fades in sun. |
| Polyester | $15 – $28 | Soft, good colors, moderate durability. |
| Nylon | $25 – $55 | Most durable; best for stairs and high traffic. |
| Wool | $50 – $120 | Premium; naturally stain resistant. |
Frequently Asked Questions
Is carpet sold by the yard or square yard?
US retailers price it per square yard. 1 sq yd = 9 sq ft. Some stores display a price per sq ft that is simply the sq yd price divided by 9.
How much carpet do I need for a 10x12 bedroom?
120 sq ft + 10% waste = 132 sq ft, or 14.67 sq yd. Round up to 15 sq yd when ordering.
Do I need to add extra for stairs?
Yes. Allow about 2.5 sq ft per stair tread+riser combination, plus a 10% waste factor. For 13 steps that is about 36 sq ft or 4 sq yd.
How do I convert sq ft to sq yd for carpet?
Divide square feet by 9. For example, 300 sq ft ÷ 9 = 33.33 sq yd. Use our sq ft → sq yd converter for quick math.
Should I buy padding separately?
Yes. Padding is usually priced per sq ft and is ordered the same square footage as the carpet. Rebond at 8 lb/cu ft is the standard residential pad.
What carpet width is standard?
US carpet comes in 12-ft wide rolls by default, with 13-ft and 15-ft options available. Wider rolls reduce seams in large rooms.
How do seams affect carpet orders?
Plan seams away from the main walking path and parallel to the light source. A 12 ft wide room fits one piece of 12 ft carpet with no seams.
How long does carpet last?
Residential carpet lasts 5 to 15 years depending on quality and foot traffic. Nylon holds up the longest; olefin is the shortest.