Wallpaper, Paint, Tile and Flooring Quantity Calculator for DIY
Enter the room width, depth and height (or an area), subtract doors and windows, add a waste allowance, and see how many rolls of wallpaper, cans of paint, or tiles and boxes of flooring you need. Square meters are also shown as Japanese tatami mats. Everything runs in your browser and nothing you type is sent to a server. You may also want the unit converter or the screen size calculator.
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For wallpaper and paint, enter the total wall area; for tile and flooring, enter the floor area.
Notes
- Wallpaper is estimated as area divided by roll area. In practice, pattern matching and cutting strips to the ceiling height waste material per strip, so use a generous waste allowance or compare with the manufacturer guidance.
- Paint coverage differs by product and also depends on how absorbent the surface is. Enter the m² per L printed on the product label.
- Diagonal layouts, pattern matching and awkward edges increase waste for tile and flooring. About 5-10% for a straight layout and 10-15% for a diagonal one is a common rule of thumb.
- Tatami conversion uses 1 mat = 1.62 m². Regional mat sizes (such as Edoma or Kyoma) differ, so the count may not match a mat count quoted for a room.
FAQ
How much waste allowance should I add?
The default is 10%. Plain wallpaper or tiles laid straight usually need 5-10%, while patterned wallpaper or diagonal layouts need 10-15% or more. Add extra if you are new to DIY or the product may be discontinued.
How are doors and windows deducted?
For wallpaper and paint, the number of doors and windows times their area is subtracted from the total wall area. Tile and flooring use the floor area, so nothing is deducted. If the deduction leaves no area, an error is shown.
Is the wallpaper roll count exact?
It is an estimate: area including waste divided by the area of one roll. Real rolls are cut into strips of ceiling height, so leftovers are wasted per strip. For patterned paper or tall ceilings, raise the waste allowance.
How is the number of paint cans decided?
Wall area x coats / coverage (m² per L) gives the liters needed, which is divided by the can size and rounded up. Coverage varies by product, so enter the figure printed on the label.
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