How to use the wallpaper calculator
- Measure the room's length and width along the floor, and the wall height. For a single accent wall, enter its width as the length and 0 as the width, and set doors and windows to 0.
- Count the doors and windows. The calculator subtracts 21 sq ft per door and 15 sq ft per window.
- Check the roll label for width, length and pattern repeat. Most rolls sold today are 20.5 in wide and 33 ft long (about 56 sq ft).
How the rolls are worked out
strip length = wall height + pattern repeat + 2 in trim
strips per roll = roll length ÷ strip length (rounded down)
strips needed = wall width to cover ÷ roll width (rounded up)
rolls = strips needed ÷ strips per roll (rounded up)
Counting strips is more accurate than dividing the wall area by the roll area, because the leftover piece at the end of each roll is usually too short to use. A large pattern repeat makes each strip longer, so you get fewer strips per roll.
Rolls for common room sizes
| Room | 8 ft walls, no repeat | 8 ft walls, 21 in repeat | 9 ft walls, no repeat |
|---|---|---|---|
| 10 × 10 ft | 6 | 7 | 8 |
| 12 × 12 ft | 7 | 9 | 9 |
| 12 × 15 ft | 8 | 10 | 10 |
| 14 × 16 ft | 9 | 11 | 11 |
Assumes 20.5 in × 33 ft rolls, 1 door and 1 window.
Tips before you buy
- Buy one extra roll, and make sure every roll has the same batch (dye lot) number.
- A "drop match" pattern lines up halfway down the next strip; use the full repeat from the label anyway.
- Some US wallpaper is still priced per single roll but sold in double rolls. Check the length on the label, not the price tag.
- Prime bare drywall before hanging so the paper can be removed later.
Frequently asked questions
How many rolls of wallpaper do I need for a 12x12 room?
With 8 ft walls, one door and one window, and standard 20.5 in × 33 ft rolls with no pattern match, about 7 rolls. Add a roll for mistakes.
How many square feet does a roll of wallpaper cover?
A standard 20.5 in × 33 ft roll is about 56 sq ft. On 8 ft walls it gives 4 full-height strips, and fewer with a large pattern repeat, so count strips rather than square feet.
What is pattern repeat?
The vertical distance before the design repeats. Each strip has to start at the same point in the pattern, so a bigger repeat wastes more paper.
Should I subtract windows and doors?
Yes, but strips still run above doors and above and below windows, so the calculator only removes the opening area, not whole strips.