Wallpaper rolls by area Calculator: measuring notes and method
Count full drops from a roll
Divide usable roll length by the required drop length and round down to find full drops per roll. Then divide the number of drops required by that yield and round up to rolls.
Check the drop length
Include trimming and any pattern-match allowance in each drop. Offcuts that cannot make another full drop are not equivalent to usable wall coverage.
CHECK A PRACTICAL EXAMPLE
Why the area estimate needs a drop check
An illustrative wall is 4 m wide and needs 2.6 m long drops including trimming. A roll is 0.53 × 10 m, with no pattern allowance here.
Area-only estimate
- Rolls to buy
- 2
- Effective coverage per roll
- 5.3 m²
Area plus 20% allowance
- Rolls to buy
- 3
- Effective coverage per roll
- 5.3 m²
The actual layout needs ceil(4 ÷ 0.53) = 8 drops. Each roll gives floor(10 ÷ 2.6) = 3 full drops, so 3 rolls are needed. Adding a generic percentage is not a substitute for checking full drops and pattern matching.
Fixed comparison in metric units. Values are illustrative unless linked to a recorded project; changing the calculator above does not change this example.
Formula
Effective roll area = (roll width − side overlap) × roll length. Rolls = area with waste ÷ effective coverage, rounded up.
Worked examples in metric and imperial units
Illustrative values match Reset example and stay fixed when you edit the calculator. Both columns describe the same calculation; converted inputs are rounded.
Metric worked example
- Total surface area
- 24 m²
- Roll width
- 0.53 m
- Roll length
- 10 m
- Overlap
- 0 mm
- Waste allowance
- 20 %
Rolls to buy: 6
Imperial worked example
- Total surface area
- 258.3339 ft²
- Roll width
- 1.7388 ft
- Roll length
- 32.8084 ft
- Overlap
- 0 in
- Waste allowance
- 20 %
Rolls to buy: 6
Follow the calculation
Lengths in this working are in metres.
- Effective width = 0.53 − 0 = 0.53 m.
- Effective area per roll = 0.53 × 10 = 5.3 m².
- Divide 28.8 m² including allowance by effective roll area and round up.
Reviewed 19 October 2026. How calculations are checked · Report a correction