Carpet & Flooring Square Footage Calculator
Flooring is bought by the square foot you waste, not the room you measure. This includes the cutting waste, the padding, and the roll width you actually get.
Broadloom truth: a 12×14 room bought off a 12 ft roll uses 12 × 14.5 = 174 sq ft of roll (your 0.5 ft runs off the length as trimming). Seamed rooms pay more waste, the waste % row is why.
How the math works
- Room area = width × length. Buy = area × (1 + waste%). Standard waste 10%; pattern-matched or diagonal layouts 15%.
- Roll math: linear feet = area ÷ roll width, rounded up to 0.5 ft. Off a 12 ft roll, a 12×14 room cuts 14.5 linear ft, the half-foot is the trimming that ends up in the garage.
- Pad = carpet area + 5% (seam and edge allowances), priced at ~$0.40/sq ft inside the installed row.
- LVP/plank: buy by length, 10% waste, underlay separate, the plank row switches the math to length-based.
How much extra carpet for waste?
10% for plain rooms, 15% for patterned goods or diagonal layouts, 20% for multi-room seaming. The waste is the difference between "measured it" and "measured it, cut it, matched the pattern."
Does carpet padding cost extra?
Yes, ~$0.35–0.50/sq ft, and it's bought by area like the carpet (plus 5%). Quotes that fold pad into "installed price" hide exactly this line, the tool shows both.
What roll width should I enter?
The width the product ships in: 12 ft broadloom is standard, 11 ft for many carpets, 6 or 10 ft for sheet vinyl. Narrower roll = more seams = more waste; the calculator raises the roll-feet number accordingly.