Wallpaper Calculator

How to use the wallpaper calculator

1. Enter the room's length and width along the floor, and the wall height from baseboard to ceiling.
2. Enter the number of doors and windows. The calculator shortens the run of wall for each one.
3. Enter the pattern repeat from the roll label. Use 0 for random-match papers such as grasscloth.
4. Open Advanced options to change the roll size (default 20.5 in × 33 ft, a common US double roll) and the waste allowance (default 10%).
5. For trimming, add about 4 in to the wall height, as York and Brewster recommend leaving roughly 2 in at the ceiling and 2 in at the baseboard.

How the strip method works

Wallpaper is hung in vertical strips (drops), so counting strips is more accurate than dividing square footage by roll coverage. The calculator works in five steps:

• Run of wall = room perimeter − 3 ft per door − 1.5 ft per window
• Strips = run ÷ roll width × (1 + waste), rounded up
• Strip length = wall height, rounded up to a whole number of pattern repeats
• Strips per roll = roll length ÷ strip length, rounded down
• Rolls = strips ÷ strips per roll, rounded up

Rounding strips per roll down matters: the leftover piece at the end of a roll is too short for another full drop, so it's waste. Windows only take out half a width because you still paper above and below them.

Single rolls vs. double rolls

In the US, wallpaper is often priced per single roll but sold in double rolls (bolts). Brewster notes that an order of 10 single rolls arrives as 5 bolts. A 20.5 in × 33 ft double roll covers about 56 sq ft. If your paper comes in a different size, enter its real width and length.

Worked examples

Bedroom, 12 × 10 ft with 8 ft walls, no repeat

One door, two windows, 20.5 in × 33 ft rolls and 10% waste. The perimeter is 44 ft and the run 38 ft, which needs 25 strips. Each roll gives 4 strips of 8 ft, so you need 7 rolls. Enter 8.4 ft to leave trimming allowance and each roll gives only 3 strips: the order rises to 9 rolls.

Same room with a 21 in pattern repeat

With 8 ft walls, each strip must be 5 repeats long, 8.75 ft, so a roll yields 3 strips and the order is again 9 rolls.

Living room, 14 × 12 ft with 9 ft walls

Two doors, three windows and a 25.25 in repeat. The perimeter is 52 ft, the room needs 27 strips, each roll gives 3, and you order 9 rolls.

Before you order

Check the match type on the label. Straight-match papers line up at the ceiling on every strip; drop-match papers line up on every other strip and can need more paper than the repeat alone suggests. Random-match papers waste the least.

Order every roll from the same run number (dye lot), the batch printed at one time, so the color is consistent from wall to wall. Buying an extra roll at the start is cheaper than trying to find a matching run later.