Carpet Calculator
Main area
L-shape extension (optional)
Carpet = room area × 1.10 (L-shaped: sum of rectangles)
How Carpet Calculations Work
Carpet is sold by the square foot or square yard (9 sq ft = 1 sq yd). Room area = length × width. A 12 ft × 12 ft bedroom is 144 sq ft. Carpet installers add 10% for seaming, closet turns, and pattern matching: 144 × 1.10 = 158.4 sq ft of carpet and padding. Carpet comes in fixed roll widths — 12 ft is most common — so actual cuts may waste material along the length depending on room shape.
Padding is purchased at the same square footage as carpet. Rebond padding (6–8 lb density) is standard for residential use. Cost varies by carpet grade: budget berber at $2–$3/sq ft installed; mid-grade plush $4–$6; premium wool $8–$12+. At $4/sq ft for 158 sq ft, material runs $632 before labor. Labor adds $1–$3/sq ft for professional install including tack strips and seaming.
Multi-room jobs sum separate areas. A 12×12 bedroom (144 sq ft) plus a 6×8 closet (48 sq ft) totals 192 sq ft, or 211 sq ft with waste. Hallways and stairs are measured separately — stairs use linear feet of runner or cap-and-band method. Patterned carpet requires more waste (15–20%) to align motifs at seams.
Remove old carpet and pad before measuring — subfloor damage affects prep cost. Concrete slabs need moisture barrier; wood subfloors need tack strips around the perimeter. Transition strips at doorways are separate from carpet area calculations.
| Room | Base Area | With 10% Waste |
|---|---|---|
| 10×12 ft | 120 sq ft | 132 sq ft |
| 12×12 ft | 144 sq ft | 159 sq ft |
| 15×20 ft | 300 sq ft | 330 sq ft |
| 12×12 + 6×8 closet | 192 sq ft | 211 sq ft |
Enter one or two rectangular sections and optional cost per square foot for carpet, padding, and price range estimates. Compare with the flooring calculator for hard-surface alternatives.
Examples
| Example | Result |
|---|---|
| 12×12 ft bedroom | 144 sq ft, 159 sq ft with padding |
| 15×20 ft living room, $5/sq ft | 330 sq ft, $1,320–$2,475 |
| 10×14 ft + 5×6 ft closet | 170 sq ft, 187 sq ft with waste |
| 12×18 ft family room | 216 sq ft, 238 sq ft with waste |
| 8×10 ft office | 80 sq ft, 88 sq ft with waste |
| 14×16 ft master, $6/sq ft | 246 sq ft, $1,180–$2,214 |
| 20×12 ft basement | 240 sq ft, 264 sq ft with waste |
Frequently asked questions
Add 10% for standard rooms. Hallways, L-shaped spaces, and patterned carpet may need 15–20% extra due to seaming and pattern matching.
Yes. Padding is cut to match carpet coverage square footage. Never reuse old padding under new carpet.
One square yard equals 9 square feet. Divide square feet by 9 when a price is quoted per square yard.