How to use the carpet calculator
- Enter the room length and width.
- Enter waste. The default 10% is a CalcTheJob planning starting point. Raise it for stairs or odd rooms.
- Enter the roll width. Most broadloom is 12 feet wide; 13-foot-6 and 15-foot goods also exist.
Installed prices are on the carpet installation cost calculator. Vinyl and laminate box counts stay on the flooring calculator.
Area, waste and roll length
Room area = length × width. Area with waste = area × (1 + waste%). Linear feet of goods = area with waste ÷ roll width — an area-equivalent length, not a seam or cut plan. Pad area matches the carpet area with waste.
A worked example: 12×15 ft room
A 12 × 15 ft room is 180 sq ft. With 10% waste you need 198 sq ft of carpet and pad, or 16.5 linear feet of 12-foot-wide goods.
Sources & assumptions
How this calculator gets its numbers. Full method: our methodology.
- Room area = length × width. Area with waste = area × (1 + waste%). Linear feet of goods = area with waste ÷ roll width. Pad area matches carpet area with waste.
- Default 10% waste and 12 ft roll width are CalcTheJob planning starting points.
- This is a carpet takeoff only, not a vinyl or laminate box count and not an installed-price page.
Sources
- HomeGuide, Carpet Installation Cost (roll-width and waste context). Used here only as background that residential broadloom is commonly sold in 12 ft widths and that waste and stairs affect the takeoff; prices themselves are on the carpet installation cost calculator.
Last reviewed . The roll width of the goods you order and a measured room sketch win.
Frequently asked questions
How much carpet for a 12×15 room?
180 sq ft of room area, or 198 sq ft with a 10% waste allowance — 16.5 linear feet of 12-foot-wide goods (an area-equivalent length, not a seam or cut plan). Pad matches the 198 sq ft.
Is the 10% waste required?
No. It is a CalcTheJob planning starting point. Simple rectangles can use less; stairs and odd rooms often need more.
Does this count vinyl or laminate boxes?
No. Those stay on the flooring calculator. This page is a carpet takeoff only.
Where do I estimate installation cost?
On the carpet installation cost calculator, which uses four independent published per-square-foot figures.