Wallpaper Calculator
Calculate how many rolls of wallpaper you need for any room. Accounts for pattern repeat, doors, and windows.
How to Calculate Wallpaper for a Room
To estimate wallpaper, measure the total perimeter of the room and multiply by the wall height to get the gross wall area. Subtract the area of doors (about 21 sq ft each) and windows (about 15 sq ft each). Divide the remaining area by the usable coverage of each roll, which depends on the roll width, roll length, and any pattern repeat waste.
Understanding Pattern Repeat
Pattern repeat is the distance between where the pattern starts and where it begins again. A larger repeat means more waste because you need to align the pattern from strip to strip. Wallpapers with no pattern repeat (solid or random textures) waste the least material. A typical pattern repeat is 12 to 24 inches, and can add 15-25% extra material to your estimate.
Single Roll vs. Double Roll
| Roll Type | Dimensions | Coverage (approx.) |
|---|---|---|
| American Single Roll (20.5") | 20.5" wide × 33 ft long | ~56 sq ft |
| American Single Roll (27") | 27" wide × 27 ft long | ~61 sq ft |
| Euro Roll | 20.5" wide × 16.5 ft long | ~28 sq ft |
Tips for Accurate Wallpaper Estimates
- Always buy an extra roll or two for mistakes, future repairs, and pattern matching at corners.
- Wallpaper is typically sold in double rolls, even though pricing is listed per single roll.
- Measure each wall individually if your room is not a perfect rectangle.
- Account for obstacles like fireplaces or built-ins by subtracting their wall footprint.
- Order all rolls from the same dye lot to avoid color variation between batches.
Do I Need Wallpaper Paste?
Pre-pasted wallpaper only needs water for activation, but many professionals still apply a thin layer of adhesive for a stronger bond. Non-pasted (unpasted) wallpaper requires a separate wallpaper paste. One gallon of paste typically covers about 4 rolls. Peel-and-stick wallpaper needs no additional adhesive at all.
Before wallpapering, make sure your drywall surface is smooth, primed, and free of imperfections — any bumps or seams will show through the paper. If you decide to paint instead of wallpaper, use our paint calculator. Compare costs with our interior painting cost guide.
Frequently Asked Questions
A 12x12 room with 8-foot ceilings has about 384 sq ft of wall area. After subtracting a door (21 sq ft) and two windows (30 sq ft), you have roughly 333 sq ft to cover. Using standard 20.5-inch rolls at 33 ft long (about 56 sq ft each), you would need approximately 6 single rolls — though pattern repeat can increase this to 7 or 8 rolls.
Pattern repeat is the vertical distance between one point in a pattern and the next identical point below it. For example, a 21-inch repeat means the design repeats every 21 inches. When hanging wallpaper, you must align these repeats between adjacent strips, which creates waste from trimming. The larger the repeat, the more wallpaper you will need. Solid and textured wallpapers typically have zero repeat.
Most wallpaper in the U.S. is priced by the single roll but sold in double-roll bolts. A single roll of 20.5-inch wallpaper covers about 56 sq ft, while a double roll covers about 112 sq ft. European rolls are typically sold individually and are shorter (about 16.5 ft long). Always check whether the listing is per single roll or double roll before purchasing.
Plan to buy 10-15% more wallpaper than your calculated estimate. This accounts for cutting waste, pattern matching, mistakes during installation, and future repairs. If your wallpaper has a large pattern repeat (over 12 inches), consider adding 20% extra. Always keep at least one extra roll for future touch-ups, since dye lots can vary between production runs.
While it is possible to wallpaper over existing wallpaper, it is generally not recommended. The old adhesive can fail, causing both layers to peel. Seams and textures from the old paper may show through the new layer. For best results, remove the old wallpaper using a steamer or removal solution, repair the wall surface, and apply a primer before hanging new wallpaper.