Metric Unit Calculator
The formula, your substituted values, and the evaluated result are shown below.
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View offerAffiliate link — we may earn a commission at no extra cost to you.Estimate the number of wallpaper units needed from area, unit coverage, and waste allowance.
This is a planning estimate. Confirm dimensions, allowances, material specifications, applicable codes, and supplier requirements before purchasing or construction.
Estimate the number of wallpaper units needed from area, unit coverage, and waste allowance.
The calculator divides the wall area by the area of one roll, adds waste, and rounds up:
Rolls = round up( wall area (m²) ÷ roll area (m²) × (1 + waste % ÷ 100) )
A standard wallpaper roll in Australia is 0.53 m wide × 10.05 m long, which is 5.3 m². Check your roll, as wider formats exist.
Wallpaper is hung in vertical strips ("drops"), so decorators often count drops instead: 1. Drops needed: 4 m ÷ 0.53 m = 7.5, so 8 drops 2. Each drop: 2.7 m wall + 0.1 m trim = 2.8 m (plus the pattern repeat, if any) 3. Drops per roll: 10.05 ÷ 2.8 = 3 whole drops 4. Rolls: 8 ÷ 3 = 2.67, so 3 rolls
Both methods agree here. On high walls or large pattern repeats, the drop method is more accurate.
| Wallpaper type | Suggested waste |
|---|---|
| Plain or random pattern | 10% |
| Small pattern repeat (under 30 cm) | 15% |
| Large pattern repeat (over 50 cm) | 20–25% |
Add the widths of all walls, divide by the roll width to get drops, work out drops per roll, then divide. A 4 × 3.5 m room with 2.4 m walls needs 29 drops at 4 drops per roll, which is 8 standard rolls before subtracting any full-height openings.
The standard is 0.53 m × 10.05 m (about 5.3 m²), but many designer papers come in other sizes.
10% for plain papers, 15% for small repeats, and 20–25% for large pattern repeats.