Carpet Calculator
Calculate square yards of carpet, padding and tack strip for any room - by roll width and seam direction.
The carpet calculator returns square yards of carpet, padding rolls and tack strip for any room. Carpet is priced in square yards (1 sq yd = 9 sq ft) but rolls come in fixed widths - typically 12 ft, with 13.5 and 15 ft rolls less common. If your room is wider than the roll, you need a seam, which means buying extra material to match the pattern across the seam. Pattern-matched carpet wastes 15% on average vs 10% for solid plush. The padding and tack strip math is straightforward: padding covers the same area as the room plus 5% waste, tack strip runs the perimeter minus door openings.
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Frequently asked questions
A 12x15 ft room is 180 sq ft, or 20 sq yards exact. With a 12 ft roll laid the long way (no seam needed since 12 ft = roll width), that is 20 sq yards + 10% waste = 22 sq yards. With seams or pattern matching, expect 23-24 sq yards. Always buy from the same dye lot - carpet color varies between production runs.
12 ft is the standard residential carpet roll width in the US - it covers most bedrooms and living rooms without seams. 13.5 ft and 15 ft rolls exist but are less common and often special-order. Wider rolls reduce seam waste in large rooms but are harder to transport and handle. Commercial carpet often comes in 6 ft rolls and 24 inch tiles.
Same square footage as the carpeted area plus 5% waste for cuts. Padding comes in 30 ft x 6 ft rolls (180 sq ft per roll). A 12x15 room (180 sq ft) needs one roll plus 5%, so 2 rolls. Common padding densities: 6 lb for bedrooms, 8 lb for living rooms, 10 lb for high-traffic areas. Higher density costs more but extends carpet life.
Tack strip runs along the perimeter of the room except across doorways. A 12x15 room has a 54 ft perimeter; subtract 3 ft for one doorway = 51 ft of tack strip. Tack strip comes in 4 ft sticks, so buy 13 sticks. Use concrete tack strip on slab floors (with masonry nails) and regular tack strip on wood subfloor.
5% for a simple rectangular room with no seams and solid color carpet. 10% standard for most installs. 15% for patterned carpet that requires seam matching - every seam wastes a pattern repeat worth of material. 20% for rooms with stairs, closets, bay windows or other obstacles that force many cuts.