Carpet Calculator
Calculate square footage, square yards, and cost for any room.
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How to Calculate How Much Carpet You Need
The carpet calculator above converts your room dimensions into square yards — the unit carpet is sold in — and provides a cost estimate by carpet grade. Understanding the math helps you shop confidently and avoid overpaying or running short.
Why Carpet Is Sold in Square Yards
Carpet is manufactured on looms in 12-foot wide rolls (occasionally 15-foot). The industry standardized on square yards decades ago. One square yard = 9 square feet. For a 15×12 room: 15 × 12 = 180 sq ft ÷ 9 = 20 square yards. That is the baseline before adding waste.
Waste Factor Explained
Carpet is cut from a roll in one continuous piece. The installer must orient the roll so the pile direction is consistent throughout the room. For a 15×12 room with a 12-foot wide roll, the installer cuts a 15-foot length — covering 180 sq ft — but must also account for 3–6 inches of trim on each edge. For rooms wider than 12 feet, a second strip is needed, creating a seam. That seam strip requires its own cut and often has significant waste.
Carpet Grades and What They Mean
Budget ($1–$2/sq ft): Olefin or low-pile polyester. Good for rentals or low-traffic areas. Lifespan 5–8 years. Mid-grade ($3–$5/sq ft): Nylon or higher-grade polyester with better pile density. Most popular choice for bedrooms and living rooms. Lifespan 10–15 years. Premium ($6–$12/sq ft): High-twist nylon, triexta, or wool. Best durability, stain resistance, and feel underfoot. Lifespan 15–25 years.
Padding (Underlay) Costs
Never skip carpet padding. It cushions every step, extends carpet life by absorbing impact, and improves insulation. Budget $0.50–$1.00 per square foot for padding. Recommended padding: 7/16-inch thickness, 6–8 lb density. Avoid very thick padding (over 1/2 inch) for cut-pile carpet — it can cause premature wear at seams.
Installation Cost
Professional installation adds $1–$2 per square foot, which includes moving furniture (usually), removing old carpet, installing tack strips, stretching and seaming the new carpet, and trimming. For the room in our example (180 sq ft), expect $180–$360 for installation labor alone. Most installers have minimums of $100–$150.
Carpet Fiber Comparison
Nylon: Most durable, best stain resistance with treatment, holds color well. Best overall value for high-traffic areas. Polyester (PET): Soft feel, excellent color vibrancy, naturally stain-resistant to water-based stains. Lower durability than nylon — avoid in heavy-traffic areas. Olefin (Polypropylene): Moisture-resistant, good for basements. Cheap but prone to crushing and matting. Wool: Natural, luxurious feel, excellent durability and resilience. Expensive and requires dry cleaning.
Frequently Asked Questions
Carpet rolls are manufactured in 12-foot widths, and the industry standardized on square yards for pricing. One square yard equals 9 square feet. Always convert your room square footage to square yards before getting quotes.
Add 10% for simple rectangular rooms, 15% for L-shapes, and 20% for patterned carpet requiring matching. Carpet cut from a roll cannot be returned, so buying extra is essential.
Professional installation with padding typically runs $3–$7 per square foot installed. A 12×15 bedroom can cost $540–$1,260 total including mid-grade carpet, padding, and installation.
Yes — padding is essential. It extends carpet life, improves comfort, and is required by most carpet warranties. Use 7/16-inch thickness at 6–8 lb density for residential rooms.
Split the L into two rectangles, measure each, add them together, then add 15–20% waste. For complex rooms, have a professional installer measure — they can minimize waste by planning the roll direction.