🎨 Guide
How Much Wallpaper Do I Need? – Complete Guide
Calculate wallpaper for any room. Learn about pattern repeats, waste factors, and standard roll sizes to avoid buying too much or too little.
The Basic Formula 🧮
Wallpaper calculation involves three simple steps: measure wall area, subtract doors/windows, then divide by roll coverage.
Total Area ÷ Roll Coverage = Number of Rolls
Add 10-20% for waste and pattern matching
Step 1: Measure Wall Area 📏
Calculate the total square footage of all walls you plan to cover.
Formula: (Wall Height × Wall Width) for each wall, then add together
Example: Room 12' × 15' with 8' ceilings.
Wall 1: 8 × 12 = 96 sq ft
Wall 2: 8 × 15 = 120 sq ft
Wall 3: 8 × 12 = 96 sq ft
Wall 4: 8 × 15 = 120 sq ft
Total wall area = 432 sq ft
Step 2: Subtract Doors & Windows 🚪🪟
Subtract the area of any openings to avoid overestimating.
Average deductions:
- Standard door: ~20 sq ft (3' × 6.5')
- Standard window: ~12-15 sq ft (3' × 4')
- Archway or large opening: measure and subtract
Example: 432 sq ft − 20 (door) − 12 (window) = 400 sq ft actual coverage needed
Step 3: Standard Roll Sizes 📜
| Roll Type | Width | Length | Coverage (sq ft) |
|---|---|---|---|
| US Double Roll | 20.5" (52 cm) | 33' (10 m) | ~56 sq ft |
| US Single Roll | 20.5" (52 cm) | 16.5' (5 m) | ~28 sq ft |
| European Roll | 21.7" (55 cm) | 33' (10 m) | ~60 sq ft |
| Wide Roll | 39" (100 cm) | 33' (10 m) | ~108 sq ft |
*Most wallpaper in North America is sold as "double rolls" (2 single rolls in one package).
Step 4: Pattern Repeat Adjustment 🔄
Patterns require matching between strips, creating waste. This is the most common mistake when buying wallpaper.
| Pattern Repeat | Waste Factor | Example |
|---|---|---|
| No repeat (solid, texture) | 5-10% | Add ~1 extra roll per 10 rolls |
| Small repeat (0-6") | 10-15% | Add 1 extra roll per 7-8 rolls |
| Medium repeat (6-12") | 15-20% | Add 1 extra roll per 5-6 rolls |
| Large repeat (12-24") | 20-30% | Add 1 extra roll per 3-4 rolls |
Complete Calculation Example 📝
Scenario: 12' × 15' bedroom, 8' ceilings, standard door + window, medium pattern repeat (12")
- Wall area: 432 sq ft
- Minus door/window (20 + 12): 400 sq ft
- US double roll coverage: 56 sq ft/roll
- Base rolls: 400 ÷ 56 = 7.14 → 8 rolls
- Medium pattern (15% waste): 8 × 1.15 = 9.2 → 10 rolls
✅ Final answer: 10 double rolls (purchase 11 to be safe)
Pro Tips for Wallpaper Shopping 💡
- Buy an extra roll — Keep it for future repairs. Different dye lots can vary slightly in color.
- Check batch numbers — Ensure all rolls have the same lot number for color consistency.
- Measure twice, buy once — Double-check all measurements before ordering.
- Account for ceiling height — Taller ceilings mean more waste per strip (pattern repeats add up).
- Know return policy — Ask about returns before buying extra rolls.
Common Mistakes to Avoid ❌
❌ Forgetting pattern repeat
The #1 mistake. A large repeat can waste 25%+ of your wallpaper.
❌ Not subtracting doors/windows
Even small openings save 1-2 rolls in a large room.
❌ Assuming all rolls are single
US double rolls contain 2 single rolls. Don't double-order by mistake.
❌ Ignoring vertical pattern match
Some patterns require offset matching (drop match), creating even more waste.
Try Our Wallpaper Calculator
Enter your room dimensions, door/window sizes, and pattern repeat. Get exact number of rolls needed — no waste, no shortage.
Calculate Now →