Carpet Calculator
Calculate how much carpet you need — enter room dimensions, carpet roll width, and waste factor.
Room Dimensions
Enter your room dimensions and click Calculate.
How Does the Formula Work?
Carpet is sold from rolls of a fixed width — typically 12 feet in the US or 4 metres in metric markets. You buy a linear length of that roll, and the installer cuts strips to cover your floor. Understanding this roll-based system is the key to accurate carpet estimation.
If your room width is narrower than the roll, you need one strip running the room length. If the room is wider, you need multiple strips, which creates a seam. For example, a 16×13 ft room with a 12 ft roll needs 2 strips of 16 ft each, totalling 32 linear feet × 12 ft wide = 384 ft² of carpet (even though the room is only 208 ft²).
Linear Length = Room Length × Strips × (1 + Waste%)
Total Carpet = Linear Length × Roll Width
This is why carpet often costs more than the raw area suggests — the roll width forces you to buy extra material. Choosing the right roll width can minimize waste. If your room is 13 ft wide, a 13.5 ft wide roll (available from some manufacturers) eliminates the seam entirely.
Carpet Pricing: Square Feet vs Square Yards
In the US, carpet is traditionally priced per square yard (1 yd² = 9 ft²). A carpet quoted at $30/yd² equals $3.33/ft². Brands like Shaw Floors, Mohawk, Stainmaster, and Dreamweaver price by the square yard. Home Depot and Lowe's often display per-square-foot pricing for easier comparison with hard flooring.
Installation cost typically runs $1–$3/ft² on top of material cost, which includes carpet pad, tack strips, seam tape, and labor. A standard 200 ft² room might cost $800–$1,600 total installed, depending on carpet quality.
Waste and Seams
Budget 10% waste for rectangular rooms and 15% for L-shaped rooms, stairs, or rooms with closets. Seam placement matters — installers orient seams away from windows and high-traffic areas to make them less visible. Patterned carpet requires extra material for pattern matching at seams, similar to wallpaper. Always discuss seam placement with your installer before ordering.
Carpet Types and Fibers
Carpet fiber determines durability, feel, and price. Nylon is the most popular residential fiber due to its exceptional resilience, stain resistance, and durability — brands like Mohawk SmartStrand, Shaw Anso, and Stainmaster offer premium nylon lines. Polyester (PET) is softer and more affordable but less resilient — it works well in low-traffic bedrooms. Triexta (PTT), marketed as SmartStrand by Mohawk, combines softness with built-in stain resistance. Olefin (polypropylene) resists moisture and mildew, making it ideal for basements and outdoor areas. Wool is the premium natural option — luxuriously soft and naturally flame-resistant but costs two to five times more than synthetic alternatives. At Home Depot, Lowe's, and Floor and Decor, carpet prices range from 1 to 5 dollars per square foot for material, with premium wool reaching 15 dollars or more.
Roll Width and Seam Planning
Carpet comes in standard roll widths of 12 and 15 feet. The calculator uses roll width to determine the most efficient layout that minimizes seams and waste. For a 14-foot-wide room, a 15-foot roll covers the full width with only 1 foot of waste. A 12-foot roll would require a seam, adding waste from the matching strip. Seams should be placed in low-traffic areas, perpendicular to windows (so light does not highlight them), and never in doorways or high-traffic paths. Professional installers plan seam placement before cutting — this calculator helps you estimate the total carpet area including the waste generated by roll-width constraints.
Carpet Padding
Carpet padding (underlayment) is essential — it provides cushion, extends carpet life, improves insulation, and absorbs sound. Standard residential padding is 7/16 inch thick with 6-pound density. Premium padding ranges from 1/2 inch to 7/8 inch at 8-pound density for a more luxurious feel. Memory foam padding offers the highest comfort but costs 50 to 100 percent more. Most carpet warranties require specific padding specifications — check the manufacturer requirements before purchasing. Padding costs 0.30 to 1.00 dollar per square foot and is sold by the square yard (9 square feet). Do not reuse old padding under new carpet as compressed padding reduces performance.
Measuring and Waste Factor
Measure the longest length and widest width of each room. For irregular rooms, measure the maximum dimensions — the excess becomes waste that is trimmed during installation. The calculator adds a waste percentage to account for trimming, pattern matching, and fitting around obstacles. Standard waste for a rectangular room with broadloom carpet is 10 percent. Rooms with many closets, alcoves, or angled walls should increase to 15 percent. Patterned carpet (which must be aligned at seams) may require 15 to 20 percent waste. Always verify measurements before ordering — carpet is cut from a roll and cannot be returned once cut.
Installation Methods
The standard installation method is stretch-in over tack strips. Tack strips are nailed around the room perimeter, padding is stapled to the subfloor, and the carpet is stretched onto the tack strips using a power stretcher and knee kicker. This method allows carpet replacement without damaging the subfloor. Glue-down installation bonds carpet directly to the subfloor using adhesive — this is standard for commercial applications and basements. Double-stick installation glues padding to the floor and carpet to the padding for the flattest, most stable result. Professional carpet installation in the US costs 1 to 3 dollars per square foot for labor, plus 50 to 200 dollars for furniture moving, old carpet removal, and disposal.
Cost Estimation
For a 15 by 20 foot living room (300 square feet): carpet at 3 dollars per square foot equals 900 dollars, padding at 0.50 dollars equals 150 dollars, tack strips and supplies at 50 dollars, and professional installation at 2 dollars per square foot equals 600 dollars — total approximately 1700 dollars. Budget carpet brings the total down to 900 dollars while premium wool pushes it to 5000 dollars or more. Home Depot, Lowe's, and Empire Today offer free in-home measurement and estimate services. This calculator determines the exact square footage and number of square yards needed so you can get accurate material quotes.
Tips & Recommendations
Most broadloom carpet in the US comes in 12 ft rolls. Some manufacturers offer 13.5 ft and 15 ft widths for wider rooms.
Seams, closets, and cutting waste consume material. 10% is the minimum; 15% for complex room shapes.
Carpet is priced per square yard in the US. Divide ft² by 9 to convert. This calculator shows both units.
Buy all carpet from the same dye lot. Colour varies between production runs, and a mismatch at the seam is permanent.
Frequently Asked Questions
How much carpet for a 16×13 ft room?
With a 12 ft roll: 2 strips × 16 ft = 32 linear ft. Total carpet: 32×12 = 384 ft² = 42.7 yd². The room is 208 ft² but you buy 384 ft² due to roll width. With 10% waste: 35.2 linear ft.
What roll width should I choose?
12 ft is standard in the US. If your room is 13 ft wide, ask about 13.5 ft rolls to avoid a seam. In metric markets, 4 m and 5 m widths are common.
Why do I need more carpet than my room area?
Carpet comes in fixed-width rolls. If your room is 13 ft wide and the roll is 12 ft, you need 2 strips — the second strip has 11 ft of usable width and 1 ft of waste.
What is the difference between ft² and yd²?
1 square yard = 9 square feet. Divide ft² by 9 to get yd². Carpet pricing in the US uses square yards; this calculator shows both.
Should I include closets?
Yes. Measure closet dimensions separately and add them to the room area, or include them in the room width measurement.
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