Material calculators
Material calculators that turn a square-footage figure into an order quantity and a budget — flooring, paint, tile, carpet, drywall and hardwood, waste factor included.
- Carpet
One roll foot covers 12 sq ft.
- Drywall
One sheet covers 32 sq ft.
- Flooring (laminate/vinyl)
One box covers 20 sq ft.
- Hardwood Flooring
One box covers 22 sq ft.
- Paint
One gallon covers 350 sq ft.
- Tile
One box covers 15 sq ft.
From square feet to what you actually buy
A square footage figure is only half an answer. Nothing on a builders' merchant's shelf is sold by the square foot: tile comes in boxes, drywall in sheets, paint in gallons, carpet off a roll of fixed width, and concrete by the cubic yard. Each of these calculators takes the area you measured, applies the waste factor that material genuinely needs, and rounds up to whole units — because you cannot buy 13.2 boxes of tile.
Why the waste factor matters more than the area
The offcuts are not padding. Every tile, plank or board that meets a wall gets cut, and the remainder is usually unusable. Ten percent is the standard allowance for a straight lay in a simple rectangular room; 15% is right for a diagonal or herringbone pattern, where every edge piece is a mitre; and 20% is prudent for wide planks or a strong repeating pattern that has to be matched across seams. A room full of corners, alcoves and doorways sits at the top of the range, and a circular or curved edge higher still.
Order the whole job at once. Tile is fired in dye lots and hardwood is milled in batches, so a replacement box bought months later frequently does not match — and keeping one spare box back is far cheaper than discovering the line has been discontinued.
Start with the measurement
If you do not yet have an area to work from, measure it first with the square footage calculator, or add up a whole property with the multi-room calculator. For a standard room size, the room size lookup already lists the material quantities alongside each dimension.