📜Wallpaper Calculator PRO
Rolls by the drop method — pattern repeat, height, and waste handled.
Dimension Diagram — updates as you type
Each vertical drop must clear wall height plus one pattern repeat — that is what eats roll coverage.
1 Walls & Pattern
Use 0 for plain or random-match papers. US single roll: 20.5 in × 33 ft.
2 Pricing & Labour
Results
Roll Plan
Exact need — add 1 spare roll at checkout (dye lots change).
Cost Breakdown
⚠️ Pre-Export Checklist
- Wall area measured (not floor area)
- Pattern repeat read from the roll label
- All rolls same pattern number AND dye lot
- One spare roll added for repairs
How to Calculate Wallpaper Rolls
Show the drop method and example ▼
The Drop Method
A US single roll holds 396 inches of paper. Strips per roll = floor(396 ÷ (height in inches + repeat)). Coverage = strips × 1.708 ft (20.5 in) × height in ft. Rolls= wall area ÷ coverage, rounded up.
Worked Example
400 sq ft, 8 ft walls, 12 in repeat:strips = floor(396 ÷ 108) = 3; coverage = 3 × 1.708 × 8 =41.0 sq ft/roll → 400 ÷ 41 = 10 rolls+ 1 spare.
Common Mistakes to Avoid
- Using nominal 56 sq ft coverage with patterned paper
- Buying exact rolls (dye lots change)
- Measuring floor area instead of wall area
- Ignoring half-drop repeat waste
Drag to rotate — Scroll to zoom
関連する計算機
Frequently used together on the same project.
Client & Quote (prints on PDF & Excel)
Adjustments (applies to exports)
Contingency is added as a separate line on the exported cost summary. Waste % is printed as an advisory reminder.
Project notes (prints on PDF & Excel)
Result compare (A/B)
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Saved rates auto-apply from your Price Library. Advanced details stay in your browser — nothing is uploaded except inside your own PDF/Excel exports.
Wallpaper math punishes guessing: a large pattern repeat can halve a roll coverage, and one short roll means a visible shade difference on the last wall. Our free wallpaper calculator uses the professional drop method — roll length divided by cut length, times strip width — so pattern repeats, wall height, and waste are all accounted for before you buy.
Enter the total wall area to cover, the ceiling height, and the pattern repeat in inches (zero for plain or random-match papers). Add the price per roll. Results show strips per roll, usable coverage per roll, rolls to order, and total cost — with the standard advice to round up, because dye lots change between print runs.
📖 この計算機の使い方
Step 1: Measure Wall Area
Measure each wall width times height, add them, and subtract large openings like doors and windows if you want a tighter count.
Step 2: Note Height and Repeat
Enter ceiling height in feet and the pattern repeat from the roll label in inches. Plain papers use zero.
Step 3: Price the Roll
Enter the price per single roll (US rolls are typically 20.5 in wide by 33 ft long).
Step 4: Order With Margin
Results round up to whole rolls. Buy the calculated count plus one spare for future repairs.
📐 巻数のストリップ法
A US single roll holds 33 feet (396 inches) of 20.5-inch-wide paper. Each drop (strip) must be wall height plus one repeat: strips per roll = floor(396 ÷ (height in inches + repeat)). Usable coverage is strips × 1.708 ft × height in ft square feet. Rolls needed equal wall area divided by coverage, rounded up. An 8 ft wall with a 12-inch repeat gives 3 strips per roll and about 41 sq ft of coverage — so a 400 sq ft room needs 10 rolls plus one spare.
⚠️ 避けたいよくあるミス
Using the nominal 56 sq ft per roll
✓ That figure ignores pattern matching. Real coverage on an 8 ft wall with a 12-inch repeat is closer to 41 sq ft — over 25 percent less than nominal.
Buying exact rolls
✓ Dye lots shift between print runs. One spare roll from the same lot beats a mismatched patch wall later.
Measuring floor area instead of wall area
✓ Wallpaper covers walls: perimeter times height, minus openings. Floor square footage is irrelevant.
Ignoring the repeat on half-drop patterns
✓ Half-drop designs waste more than straight matches. When in doubt, round the repeat up, not down.
💡 プロのヒント
Start hanging on the least visible wall so the final awkward join lands behind a door.
Book (fold pasted sides together) each strip and let it relax the booked time on the label.
Check every roll label: same pattern number AND same dye lot before cutting anything.
Prime with a wallpaper primer — future removal takes minutes instead of days.
❓ よくある質問
Four 8 ft walls total about 384 sq ft. With a 12-inch repeat (~41 sq ft per roll), order 10 rolls plus one spare.
The vertical distance before the design repeats. Each strip must be cut a multiple of the repeat plus wall height, which is what eats coverage.
A US single roll is 20.5 in × 33 ft (~56 sq ft gross). After pattern matching on 8 ft walls, expect 30 to 40 sq ft of usable coverage.
Never on the same wall. Lot-to-lot shade shifts are subtle on the roll and obvious on the wall.
🏗️ 実際の用途
Wallpaper estimates cover accent walls, bedrooms, dining rooms, powder rooms, and commercial corridors. Designers use the drop method daily because clients pick large-repeat murals that devastate naive square-foot math. Powder rooms are the classic trap: tiny area, high repeat, and a pedestal sink that wastes two full drops.
Our free wallpaper calculator uses the professional drop method to count rolls with pattern repeat accounted for. Use it for accent walls, bedrooms, dining rooms, and commercial spaces with US single rolls. Enter wall area, height, and repeat for an instant order quantity with waste built in.
✅Method, Sources & Review
Maintained by theBuildingCalc methods desk· Last reviewedSeptember 23, 2026. This calculator implements the standards and references below; every figure can be rechecked against the formulas and worked example on this page.
Results are estimates, not engineering advice. Verify against local codes and licensed professionals for structural, electrical, and gas work. See ourTerms. Spotted an error? Report it— corrections ship with the next review.