Wallpaper Calculator
Estimate wallpaper rolls from total wall length and height, subtract major openings, then use the usable square-foot coverage for the exact roll you plan to purchase.
Wallpaper roll formula
Gross wall area is total wall length multiplied by wall height. Large doors and windows can be subtracted before any waste or pattern allowance is applied. The resulting purchase area is divided by usable roll coverage and rounded up to whole rolls.
rolls = ceil(net wall area × (1 + allowance %) ÷ usable coverage per roll)
Nominal roll area is not always usable coverage
Wallpaper can require extra material because strips must be cut to wall height and patterns may need to align between drops. A large pattern repeat can reduce the area you can actually use from a roll. For that reason, this calculator keeps usable coverage editable instead of assuming every square foot printed on a roll becomes wall coverage.
If the retailer or manufacturer provides a project-specific roll yield, use that value. Otherwise include an allowance that reflects the pattern and room layout.
Measure the room before ordering
Add the lengths of all walls to get total wall length, then use the finished wall height. Subtract major openings only when doing so matches the installation plan; narrow areas above doors and around windows still consume full-width strips in many layouts.
Related tools: Paint Calculator · Drywall Calculator · Interior Calculators.
Example: wallpaper drops can use more rolls than area suggests
Imagine a 12 ft wide wall that is 9 ft high. The chosen wallpaper is a hypothetical 2 ft wide roll with 30 ft of usable length, so the wall needs ceiling(12 ÷ 2) = 6 full-width drops. If each drop can be cut to exactly 9 ft, one roll yields floor(30 ÷ 9) = 3 drops, or 2 rolls total. But if aligning the selected pattern requires a usable cutting length of 11 ft per drop, one roll yields only 2 drops and the wall requires 3 rolls.
Simply dividing the 108 sq ft wall area by nominal 60 sq ft roll area would suggest 2 rolls and miss that pattern constraint. The actual repeat, drop match, usable roll length and trims come from the selected product. The calculator accepts an effective usable coverage figure; for complex patterns, check a strip-by-strip cut plan first.
Wallpaper roll examples with explicit assumptions
These examples show how the same formula reacts to wall area, openings, usable roll coverage and an optional pattern allowance. The coverage values are example inputs, not universal roll sizes.
| Scenario | Net area | Usable coverage | Allowance | Whole rolls |
|---|---|---|---|---|
| 40 ft of wall × 8 ft high | 320 sq ft | 56 sq ft/roll | 0% | 6 |
| 40 ft of wall × 8 ft high + 10% allowance | 320 sq ft | 56 sq ft/roll | 10% | 7 |
| 50 ft of wall × 8 ft high, 20 sq ft openings | 380 sq ft | 50 sq ft/roll | 0% | 8 |
Plan the rest of the wall-finish project
Wallpaper quantity is only one part of a room finish. Use the Drywall Calculator when wallboard quantity is still unknown, the Paint Calculator for painted surfaces, or return to Interior Calculators for related project tools.