Inputs
Formula used
1) Effective perimeter
Effective Perimeter = Perimeter − Openings Width (optional)
2) Drop length
Base Drop = Wall Height + Trim Allowance
If Pattern Repeat > 0, Drop = ceil(Base Drop / Repeat) × Repeat
3) Rolls required
Strips Needed = ceil(Effective Perimeter / Roll Width)
Strips Per Roll = floor(Roll Length / Drop)
Base Rolls = ceil(Strips Needed / Strips Per Roll)
Rolls Incl. Waste = ceil(Base Rolls × (1 + Waste%/100))
How to use this calculator
- Measure the room perimeter and the finished wall height.
- Add the total width of major openings, if you want to deduct them.
- Enter the wallpaper roll width and roll length from the label.
- For patterned wallpaper, enter the pattern repeat value.
- Set trim allowance and waste percentage to match site practice.
- Press Calculate to see rolls needed, strips, and cost estimates.
- Use CSV or PDF outputs for procurement and site records.
Example data table
| Perimeter | Height | Roll (W×L) | Repeat | Waste | Rolls needed |
|---|---|---|---|---|---|
| 16.0 m | 2.7 m | 0.53 m × 10.05 m | 0.00 m | 10% | 6 |
| 20.0 m | 3.0 m | 0.53 m × 10.05 m | 0.64 m | 15% | 9 |
Professional guide to wallpaper roll takeoff
1) Scope and measurement discipline
Wallpaper takeoff starts with consistent field measurements. Record the finished perimeter at the wallpaper line, then confirm wall height at multiple points to capture ceiling variation. Note soffits, columns, returns, and areas behind millwork. These details affect strip count more than total square area.
2) Openings and deductions
Large openings can reduce required strips if their combined width is deducted from the perimeter. For smaller windows, many teams avoid deductions because offcuts around frames are rarely reusable. Use deduction when door banks or glazing spans remove several full strip widths.
3) Roll geometry and strip planning
Roll width controls how many strips are needed, while roll length controls how many strips fit per roll. The calculator converts units to meters, then divides effective perimeter by roll width to estimate strips. Next, it divides roll length by the working drop length to estimate strips per roll.
4) Pattern repeat impact
Patterned wallcoverings require aligning motifs at seams. That alignment forces the drop length to round up to the next whole repeat. Even a moderate repeat can reduce strips per roll, increasing roll count. Always confirm the repeat from the manufacturer label, not a catalog photo.
5) Trim allowance and site tolerances
Trim allowance covers plumb corrections, top and bottom trimming, and minor height variation. For standard rooms, 0.10 m is common, but increase it for crown moulding, uneven slabs, or complex reveals. Underestimating trim can cause a shortfall near completion.
6) Waste management and procurement buffers
Waste percentage addresses damaged strips, mis-cuts, and unusable offcuts. Plain papers may work with 10%, while bold patterns and tight schedules often require 15% to 20%. Ordering from the same batch reduces shade variation risk during touch-ups.
7) Cost planning and documentation
Add optional roll price and adhesive allowance to produce a quick budget. Export results to CSV for procurement logs, and use the PDF for site sign-off. Keep records of roll batch numbers and room identifiers for maintenance and future repairs.
8) Worked example using sample data
Example: Perimeter 16.0 m, height 2.7 m, roll 0.53 m × 10.05 m, repeat 0.00 m, trim 0.10 m, waste 10%. The calculator estimates 31 strips, 3 strips per roll, and 6 rolls including waste. Adjust waste or repeat to test sensitivity.
For high-quality finishes, confirm substrate readiness before ordering quantities. Record wall moisture, check for glossy paints, and plan primer or liner requirements. Sequencing matters: start from the most visible focal wall, keep roll direction consistent, and label each drop location. For multi-room packages, group takeoffs by elevation and batch to minimize shade variation and simplify on-site distribution.
FAQs
1) Should I subtract doors and windows?
Subtract only when openings remove several full strip widths. Small windows often create offcuts that cannot be reused, so deducting them can under-order wallpaper.
2) Why does pattern repeat increase roll count?
The drop length rounds up to the next whole repeat for seam alignment. That extra length reduces strips per roll, which increases the number of rolls needed.
3) What trim allowance is reasonable?
Many projects use about 0.10 m per drop. Increase allowance for uneven floors, tall ceilings, crown moulding, or tight detailing where extra trimming is expected.
4) What waste percentage should I use?
Use 10% for simple layouts and plain patterns. Use 15% to 20% for complex rooms, bold repeats, inexperienced crews, or strict completion deadlines.
5) How do I handle different roll sizes?
Enter the roll width and roll length exactly as supplied. The calculator converts units automatically. Recalculate if you switch product lines, as coverage per roll changes significantly.
6) Can I use area instead of perimeter?
Strips are driven by perimeter and roll width, not only area. Area methods ignore strip layout, repeats, and roll length limits, so they are less reliable for ordering.
7) Why do I get zero strips per roll?
Zero occurs when the calculated drop length exceeds roll length. Reduce wall height, lower repeat/trim, or choose longer rolls. Confirm the repeat value is entered in correct units.
Accurate roll counts reduce delays and avoid costly reorders.