Material calculator
Estimate how much material your project needs before you buy it: paint, flooring or wall framing. Enter your measurements and the calculator rounds the buy quantity up, then shows the arithmetic behind the number, so you can check it against your own notes.
Getting the amount right is the easy way to save. Too little means a second trip to the store in the middle of the job. Too much means paying for material you will never use.
- Pick paint, flooring or lumber.
- Enter your measurements and get the buy quantity, rounded up.
- Read the math step by step, and add a price to see the cost.
Free to use, no account needed.
One gallon covers about 350 sq ft per coat. A door subtracts 21 sq ft, a window 15 sq ft.
Paint needed
3 gallons
- Wall area: 2 × (12 + 11) × 9 = 414 sq ft
- Doors and windows: 1 × 21 + 2 × 15 = 51 sq ft
- Surface to paint: 414 − 51 = 363 sq ft
- Paint: 363 sq ft × 2 coats ÷ 350 sq ft per gallon = 2.1, rounded up to 3 gallons
These are buy-quantities for planning, not a guarantee — product coverage varies, and a pro should size anything structural. Always check the label and your local permit requirements.
What each calculator works out
Paint
Work out how many gallons to buy for a room. Add the wall height, how many coats you want, and how many doors and windows to subtract. One gallon covers about 350 sq ft per coat, and the estimate rounds up so you are not caught short.
Flooring
Work out how many boxes to buy. Enter the room size, the waste allowance for cuts (10% covers most straight-lay rooms, 15% for angled or patterned layouts) and the coverage on the box, and it tells you the boxes and roughly how much flooring that is. Use it for anything sold by the box or the square foot, like laminate, vinyl or tile.
Lumber
Work out how many 8 ft 2×4 boards a stud wall needs: the studs at 16 in or 24 in spacing, plus a double top plate and a bottom plate. Add corner and blocking lumber separately, and check with a pro before you frame a load-bearing wall.
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