Carpet Calculator
Calculate square footage and square yards of carpet needed for up to 3 rooms.
Includes 10% waste factor, roll-width considerations, and padding estimate.
Carpet is one of the few flooring materials still sold primarily in square yards — a holdover from pre-metric industry tradition. Understanding how the material is manufactured and cut is essential to accurate estimating.
Why Square Yards Matter
The carpet industry standardized on square yards long before metric conversion was considered in the US. One square yard = 9 square feet. A 12×15 foot bedroom = 180 sq ft = 20 sq yards. Installers, retailers, and pricing are all quoted per square yard, so you need to convert your measurements.
The 12-Foot Roll Width Rule
Carpet is manufactured in rolls that are 12 feet wide (with some products at 13'2" or 15"). This has a major implication for estimating: any room dimension under 12 feet can be cut from a single lengthwise strip with no seam. Any room wider than 12 feet will require a seam where two strips meet.
Seam placement is an art. Professional installers position seams perpendicular to the main light source in the room (typically the window) because light raking across a seam parallel to the window makes it visible. Seams should also be placed in low-traffic areas where possible.
Waste Factors
For solid-color or textured carpet with no pattern: 10% waste is a safe allowance for cuts, seams, and room irregularities.
For patterned carpet (geometric, floral, etc.): waste increases significantly based on the pattern repeat. A 24-inch pattern repeat on a 15-foot room length means you may lose up to 2 feet per strip (one pattern repeat) to align each piece. Professional estimators add 15–20% for patterned carpet.
Carpet Pad
Never forget the carpet pad. Pad is installed under the carpet and dramatically affects comfort, noise reduction, and carpet lifespan. Standard residential pad: 6 lb density rebond foam, ½" thick. Premium pad: 8 lb, ½"–⅝" thick. Pad is sold per square yard and should match your carpet yardage estimate. Budget an additional $2–$4/sq yd for pad.
Tack Strips and Seam Tape
Tack strips run along the perimeter of every room, holding the stretched carpet in place. Budget approximately 1 linear foot of tack strip per linear foot of wall. Standard cost: $0.50–$1.00 per linear foot installed.
Stair Calculation
Each stair step requires roughly 1 square foot of carpet to cover the tread and riser. A standard 13-step staircase needs 13–17 sq ft of additional carpet (the higher end accounts for the extra carpet wrapped under each tread nose). If ordering carpet for multiple rooms and stairs, add this separately.
Real Estimating Example
Two bedrooms:
- Room 1: 12×15 = 180 sq ft = 20 sq yd
- Room 2: 11×13 = 143 sq ft = 15.9 sq yd
- Total: 323 sq ft = 35.9 sq yd
- With 10% waste: 35.9 × 1.10 = 39.5 → order 40 sq yd
- At $8/sq yd carpet + $3/sq yd pad + $4/sq yd install = $15/sq yd × 40 = $600
Cost Ranges
- Builder-grade carpet + installation: $5–$9/sq yd
- Mid-range carpet + installation: $9–$15/sq yd
- Premium carpet + installation: $15–$30+/sq yd
Prices vary significantly by region. Always get 2–3 quotes from local installers.