Wallpaper Calculator
Calculate how many single rolls of wallpaper you need for a room's walls after pattern-repeat waste, plus total cost.
How this calculator works
A single roll of wallpaper covers roughly 25 usable square feet once you account for trimming and pattern-matching waste between strips. This calculator multiplies total wall length by wall height to get wall area, then divides by 25 sq ft per roll and rounds up.
Formula: Rolls = (Total wall length ft × Wall height ft) ÷ 25 usable sq ft per roll, rounded up.
Worked example
A room with 40 ft of total wall length and an 8 ft ceiling (320 sq ft):
- Wall area: 40 × 8 = 320 sq ft
- Rolls: 320 ÷ 25 = 12.8 → rounds up to 13 rolls
- At $45/roll, that’s $585.00 before waste.
- With 10% waste added: 13 × 1.1 = 14.3 → rounds up to 15 rolls, or $675.00.
Coverage reference
| Total wall area | Rolls needed |
|---|---|
| 80 sq ft | 4 rolls |
| 320 sq ft | 13 rolls |
| 1,280 sq ft | 52 rolls |
How to measure your room
Walk the room’s perimeter and add up the length of every wall being papered, then multiply by ceiling height for total wall area. If your wallpaper has a large pattern repeat, add extra beyond the built-in waste allowance, and confirm whether your supplier sells single or double rolls before placing an order.
Frequently asked questions
How much wall area does one roll of wallpaper actually cover?
A single roll is nominally about 36 sq ft, but usable coverage after trimming for pattern matching and seam alignment is closer to 25 sq ft. This calculator uses that 25 sq ft usable figure, which is why the roll count is higher than a simple room-area-divided-by-36 calculation.
What's the difference between single and double rolls?
A double roll is simply two single rolls packaged together on one larger tube — it covers twice the area of a single roll (about 50 usable sq ft) but is priced and sold as one unit. If your supplier sells double rolls, divide this calculator's single-roll count by 2 and round up.
Why does pattern repeat matter so much for wallpaper waste?
Every strip has to align with the one next to it, so large pattern repeats (18 in or more) force you to cut and discard more material per strip than a small or random-match pattern would. Bold large-scale patterns can push effective usable coverage well below the 25 sq ft/roll this calculator assumes — check your specific paper's pattern repeat before ordering close to the line.
What do the length and width fields mean for a wallpapered room?
Length is your total combined wall length (add up each wall as you go around the room, same as painting), and width is the wall height from floor to ceiling. Subtract large openings like a bay window or French doors if they're a significant fraction of a wall's area.
Should I order extra wallpaper beyond the waste allowance?
Yes, especially for a large or complex pattern — many installers recommend keeping at least one extra roll from the same dye lot for future repairs, since wallpaper runs vary slightly in color between production batches and a mismatched patch is very noticeable.
Estimates only. Verify quantities with your supplier before purchasing.