Wallpaper Calculator
Enter the total width of the walls you're papering, the ceiling height and the pattern repeat from the label. You'll get the strip length, strips per roll and the number of rolls to buy.
- Tested formulas
- Feet or metric
- Printable shopping list
2 What to buy
Updates as you type| Strips across the walls | 27, less 3 full strips over doors and windows |
|---|---|
| Strips per roll | 3 (396" roll ÷ 105" strip, rounded down) |
| Rolls | 24 ÷ 3 = 8 |
| Wall area | 368 sq ft (each roll is 56.4 sq ft before trimming) |
Buy every roll from the same batch (lot) number, since colors vary slightly between print runs. Sherwin-Williams suggests buying an extra roll for repairs and mistakes.
Quick answer
Rolls = strips needed ÷ strips per roll, rounded up. Each strip is the wall height plus trim, rounded up to whole pattern repeats. For 46 ft of 8 ft walls with a 21" repeat on 20.5" × 33 ft rolls, that's 3 strips per roll, 24 strips and 8 rolls.
Wallpaper rolls for common rooms
| Room | No repeat | 12" repeat | 21" repeat |
|---|---|---|---|
| 10 × 10 ft | 7 | 7 | 7 |
| 12 × 12 ft | 9 | 9 | 9 |
| 12 × 14 ft | 10 | 10 | 10 |
| 14 × 16 ft | 11 | 11 | 11 |
| 16 × 20 ft | 14 | 14 | 14 |
8 ft walls, 20.5" × 33 ft rolls, one door, two windows, 4" trim allowance. Use the calculator above for your exact size.
Why we count strips, not square feet
Dividing the wall area by a roll's square footage undercounts, because every strip has to be cut to a whole pattern repeat and the leftover end of each roll is often too short to use. So the calculator works the way paperhangers and Brewster's estimator do: it works out how many full-height strips fit on one roll, and how many strips go around the room.
Worked example: a 12 × 11 ft bedroom with 8 ft walls
- Total wall width: 12 + 11 + 12 + 11 = 46 ft.
- The wall is 96" plus 4" for trimming, 100". With a 21" pattern repeat, each strip has to be a whole number of repeats: 5 × 21 = 105" per strip.
- A 20.5" × 33 ft roll is 396" long, so it gives 3 strips (396 ÷ 105, rounded down).
- 46 ft is 27 strips around the room. The door and the two 3 ft windows each save one full strip, leaving 24 strips. The short pieces above and below them come from roll offcuts.
- 24 ÷ 3 = 8 rolls.
Roll sizes
- Most wallpaper sold in the US today comes in rolls about 20.5 inches wide and 33 ft long (about 56 sq ft), Brewster's standard size.
- York also sells 27 inch × 27 ft double rolls (about 61 sq ft).
- European rolls are 0.53 × 10.05 m, about 57 sq ft, roughly a US double roll.
- Some sellers still price by the single roll but ship double rolls. Check what one "roll" means before you order.
Tips before you order
- Large repeats cost more paper. A big pattern can waste up to one full repeat on every strip. Use the repeat on the label, not a guess.
- Buy one batch. Check the batch or lot number on each roll; different print runs can differ slightly in color.
- Get a spare. Sherwin-Williams suggests an extra roll. If you run short, the same batch may be gone.
Frequently asked questions
How many square feet does a roll of wallpaper cover?
A US double roll (20.5" × 33 ft) is about 56 sq ft, and a European roll about 57 sq ft. You get less than that on the wall once strips are cut to the pattern repeat. Sherwin-Williams counts about 25 usable sq ft per single roll with no repeat, falling to 18 with a 19 to 23 inch repeat.
How does pattern repeat affect how much wallpaper I need?
Each strip must be cut to a whole number of repeats, so a bigger repeat means more waste per strip and often fewer strips per roll. The calculator rounds each strip up to whole repeats, so the roll count already includes that waste.
Should I subtract doors and windows?
Only where an opening is wider than a full roll width, which saves one strip. Above and below windows and doors you still need paper, so small openings don't save a roll.
How much extra wallpaper should I buy?
The strip method already includes trimming waste. Buy one extra roll from the same batch for mistakes and future repairs.
Last reviewed 2026-10-23. See how we calculate for our sources and assumptions.