Wallpaper Calculator
Calculate how many rolls of wallpaper you need for your room, accounting for pattern repeats and waste. See also Paint Calculator and Flooring Calculator.
Room Dimensions
Standard: 21 sq ft each
Standard: 15 sq ft each
Wallpaper Roll Specifications
How to Calculate Wallpaper Needed
Calculating wallpaper requirements involves measuring your room's walls, accounting for doors and windows, and factoring in the wallpaper roll dimensions and pattern repeat. Pattern matching is the biggest source of waste — a large pattern repeat can increase the number of rolls needed by 15-25%. Always buy an extra roll or two for mistakes and future repairs.
Wallpaper Calculation Formula
Wall Area = 2 x (Length + Width) x Height
Net Area = Wall Area - Doors - Windows
Strips per Roll = Roll Length / (Wall Height + Pattern Repeat)
Usable Area per Roll = Strips x Roll Width (ft) x Wall Height
Rolls Needed = (Net Area x 1.10) / Usable Area per Roll
Example Calculation
Room: 15 ft x 12 ft x 9 ft, 1 door, 2 windows
Roll: 20.5 in wide x 33 ft long, no pattern repeat
Wall Area: 2 x (15 + 12) x 9 = 486 sq ft
Net Area: 486 - 21 - 30 = 435 sq ft
Strips per roll: 33 / 9 = 3 strips
Usable per roll: 3 x 1.71 ft x 9 = 46.1 sq ft
Rolls needed: (435 x 1.10) / 46.1 = 11 rolls
Understanding Pattern Repeat and Waste
Pattern repeat is the vertical distance between where the pattern begins to repeat. When hanging wallpaper, each strip must be aligned so the pattern matches at the seams. This means you may need to trim significant amounts from each strip to achieve alignment, increasing waste.
- No repeat (0 inches): Minimal waste, easiest to hang. Textures and solids.
- Small repeat (12 inches): Moderate waste, 10-15% extra material needed.
- Medium repeat (18 inches): More waste, 15-20% extra material needed.
- Large repeat (24+ inches): Maximum waste, 20-25% extra material needed.
Standard Wallpaper Roll Sizes by Region
| Region | Roll Type | Width | Length | Coverage |
|---|---|---|---|---|
| US | Single Roll | 20.5 in (52 cm) | 33 ft (10 m) | ~56 sq ft |
| US | Double Roll | 20.5 in (52 cm) | 66 ft (20 m) | ~112 sq ft |
| US | Wide Single | 27 in (69 cm) | 27 ft (8.2 m) | ~60 sq ft |
| EU | Standard | 21 in (53 cm) | 33 ft (10.05 m) | ~57 sq ft |
| EU | Metric | 20.5 in (52 cm) | 33 ft (10.05 m) | ~56 sq ft |
| EU | Wide | 41 in (106 cm) | 33 ft (10.05 m) | ~113 sq ft |
Frequently Asked Questions
How many extra rolls should I buy?
Buy 1-2 extra rolls beyond what the calculator suggests. This accounts for cutting mistakes, damaged strips, and future repairs. Wallpaper from different batches (dye lots) may have slight color variations.
What is the difference between a single roll and double roll?
In the US, wallpaper is priced per single roll but sold in double rolls (bolts). A double roll is simply twice the length of a single roll. This gives you more flexibility in cutting strips with less waste.
Should I wallpaper behind furniture?
It depends on whether you plan to rearrange furniture. If the piece will always be in the same spot, you can skip that section. However, wallpapering the entire room ensures flexibility and a complete look if furniture is moved.
How do I handle corners and obstacles?
Never wrap wallpaper around corners — cut and overlap slightly. For outlets and switches, hang the paper over them and cut an X shape, then trim. This adds minimal waste but ensures clean results.
Can I wallpaper over existing wallpaper?
It is possible but not recommended. Old wallpaper may bubble, peel, or show through. For best results, remove old wallpaper, repair the wall surface, and apply primer before hanging new wallpaper.
What is a straight match vs drop match pattern?
A straight match means the pattern aligns at the same point on each strip. A drop match means alternating strips are offset (usually by half the repeat), requiring more careful planning and typically more waste.
How long does wallpaper last?
Quality wallpaper properly installed can last 15-20 years or more. Vinyl and non-woven wallpapers are the most durable. Factors affecting longevity include humidity, sunlight exposure, and wall preparation quality.