Wallpaper Calculator
Figure out how many rolls you need or how much area a set of rolls will cover, accounting for roll size, pattern repeat, and trim.
Calculation Steps
Practical Guide
Wallpaper Calculator: Fast, Accurate Roll Counts for Any Room
Use the calculator above to size your wallpaper like a pro. This guide mirrors its fields—room size, openings, roll width/length, and pattern repeat—so you can order the right number of rolls with confidence and minimal waste.
Quick Start
- 1 Measure each wall’s length and the finished height you’ll paper (floor to ceiling or to a cap/rail). Subtract major openings (doors, large windows) for a cleaner estimate.
- 2 Enter your roll width, roll length, and pattern repeat. If the label says “half-drop,” select that match type.
- 3 In the calculator, choose whether you’re working by perimeter (sum of wall lengths) or by total wall area. Both yield the same result when openings are handled consistently.
- 4 Review strips per roll and total strips needed, then round up to whole rolls. Add a small contingency for waste and future repairs.
Tip: Always verify whether the store sells in single or double rolls. Enter the actual width and total usable length for what you’re buying.
Watch-out: For patterned paper, the calculator increases strip length to the next repeat. If you skip this, your roll count will be short.
Choosing Your Method
Method A — By Room Perimeter
Great for rectangular rooms or when you can quickly add wall lengths.
- Quick mental check on site.
- Pairs well with standard-height rooms.
- Easy to see the impact of one extra wall.
- Requires accurate subtraction for doors and large openings.
- Less precise for complex layouts with niches/soffits.
Strips needed \(\\approx \\left\\lceil \\dfrac{\\text{Perimeter}}{w} \\right\\rceil\), where \(w\) is roll width (same units).
Method B — By Net Wall Area
Best when you have drawings with wall areas or many unique wall shapes.
- Handles complex shapes/openings cleanly.
- Useful for estimating material cost early.
- Still must account for repeats when converting area to strips.
- Requires converting area back to strip count using width.
Net area \(A_{\\text{net}} = \\sum L_i H_i – \\sum A_{\\text{openings}}\\).
What Moves the Number the Most
Pattern repeat
Repeat increases each strip’s effective length: \(H^{\\*} = \\lceil H/R \\rceil\\times R\) (straight match). Bigger \(R\) ⇒ fewer strips per roll.
Match type
Half-drop (or 1/3-drop) adds an extra half (or fraction) repeat to align motifs, increasing waste.
Roll width
Wider papers need fewer strips for the same perimeter—major impact on totals.
Usable roll length
The printed length minus starter/trim waste controls how many full-height strips you get per roll.
Openings & obstacles
Doors and large windows reduce total strips. But small windows can increase waste due to partials.
Contingency
Add 5–15% for offcuts, miscuts, and future patching—more for bold patterns or DIY installs.
Worked Examples
Example 1 — US Imperial (straight match)
- Room: 12 ft × 15 ft, 8 ft ceiling ⇒ perimeter \(= 54\\,\\text{ft}\)
- Openings: 1 door (21 ft²), 2 windows (each 12 ft²) ⇒ subtract 45 ft²
- Paper: 20.5 in width (1.708 ft), 33 ft length (per roll)
- Pattern repeat: 10 in (0.833 ft), straight match
1
Effective strip length:
\(H^{\\*} = \\lceil 8/0.833 \\rceil \\times 0.833 = \\lceil 9.6 \\rceil \\times 0.833 = 10 \\times 0.833 = 8.33\\,\\text{ft}\)
2
Strips per roll:
\(N_{\\text{roll}} = \\left\\lfloor \\dfrac{33}{8.33} \\right\\rfloor = 3\\) full-height strips.
3
Strips needed:
\(\\left\\lceil \\dfrac{54}{1.708} \\right\\rceil = \\left\\lceil 31.6 \\right\\rceil = 32\\) strips.
4
Rolls (before contingency): \(\\left\\lceil 32/3 \\right\\rceil = 11\\) rolls. Add 10% ⇒ order 12 rolls.
If your supplier sells “double rolls” of the same width but ~66 ft long, you’d get ~6 strips per double roll. In that case you’d order 6 double rolls (12 single-roll equivalents).
Example 2 — Metric (half-drop match)
- Room: perimeter \(= 34\\,\\text{m}\), height \(= 2.6\\,\\text{m}\)
- Paper: 53 cm width (0.53 m), 10 m length
- Pattern repeat: 64 cm (0.64 m), half-drop
1
Effective strip length (half-drop):
add half a repeat then round up to next repeat: \(H’ = 2.6 + 0.32 = 2.92\\,\\text{m}\).
Round to a multiple of 0.64: \(H^{\\*} = \\lceil 2.92/0.64 \\rceil\\times 0.64 = \\lceil 4.56 \\rceil \\times 0.64 = 5 \\times 0.64 = 3.20\\,\\text{m}\).
2
Strips per roll: \(N_{\\text{roll}} = \\left\\lfloor 10/3.20 \\right\\rfloor = 3\\).
3
Strips needed: \(\\left\\lceil 34/0.53 \\right\\rceil = \\left\\lceil 64.15 \\right\\rceil = 65\\).
4
Rolls: \(\\left\\lceil 65/3 \\right\\rceil = 22\\) rolls. Add 10% (patterns/repairs) ⇒ 24 rolls.
Metric bolts commonly come as 0.53 m × 10 m. Some premium lines vary—always enter the exact label values.
Pattern Matches & Variations
Match type and repeat drive waste. Use the table below to sanity-check the allowance your calculator adds to each strip.
| Type / Variation | How to Allow in Math | Typical Extra Waste | Notes |
|---|---|---|---|
| Straight match | \(H^{\\*} = \\lceil H/R \\rceil\\times R\) | +5–10% | Motifs align horizontally; simplest repeat handling. |
| Half-drop (offset) | Add \(R/2\) then round: \(H^{\\*} = \\lceil (H+R/2)/R \\rceil\\times R\) | +10–15% | Common for large prints; increases offcuts. |
| Random / free match | Use \(H^{\\*} \\approx H + \\text{trim allowance}\\) | +3–6% | Textured/grasscloth often behaves like free match. |
| Wide papers (e.g., 27–36 in) | Reduce strips: \(\\lceil \\text{Perimeter}/w \\rceil\) | Varies | Fewer seams, but mind corners and handling. |
| Repeat > 24 in (600 mm) | Large \(R\) ⇒ fewer strips/roll | +15–20% | Test with one wall before bulk ordering. |
- Order from the same dye lot to avoid shade variation.
- Confirm whether lengths are pre-trimmed or need double-cutting.
- Account for baseboards/crowns only if papering above/below them.
- For stairwells/tapered ceilings, measure the tallest point.
Buying, Logistics & Practicalities
Selection & Specs
- Roll sizing: Verify width and total usable length (single vs. double roll conventions vary by region/brand).
- Material: Vinyl is scrubbable; paper and non-woven breathe better. Choose for room humidity and cleaning needs.
- Adhesive: “Paste-the-wall” simplifies install and removal; pre-pasted needs water activation.
Install & Logistics
- Prime and smooth walls; seal stains before papering.
- Snap a plumb line for the first strip; work from the most visible corner.
- Cut long motifs at eye level; reserve offcuts for over-door/window returns.
Sanity Checks
- Dry-fit one strip set to validate repeat math before opening all rolls.
- Keep one unopened roll for repairs; returnable policy varies—confirm before purchase.
- Photograph lot numbers on arrival; mix boxes to blend dye lots only if identical.
Local codes rarely govern wallpaper directly, but fire ratings and wipeability standards can apply in commercial spaces—check project specs.
Frequently Asked Questions
How do I calculate wallpaper rolls quickly?
Use perimeter ÷ roll width to get strip count, then divide by strips per roll: \(N_{\\text{rolls}} = \\left\\lceil \\dfrac{\\lceil \\text{Perimeter}/w \\rceil}{\\lfloor L/H^{\\*} \\rfloor} \\right\\rceil\),
where \(H^{\\*}\) adjusts for pattern repeat. Add 5–15% for waste.
What is a “double roll,” and how does it affect coverage?
Many US suppliers price in double rolls (two single-roll lengths on one bolt). Enter the actual width and total length shown on your label—coverage is then computed directly and avoids confusion.
Do I subtract windows and doors?
Yes for large openings (doors, wide windows). For small windows, you often need partial strips around reveals, so the offcuts can offset the subtraction—our calculator’s strip logic handles this realistically.
How much extra wallpaper should I buy?
5–10% for simple straight matches and pro installs; 10–15% for half-drop/large repeats or DIY. Keep one sealed roll for future patching if possible.
What if my ceiling isn’t level?
Measure the tallest wall height and use that as \(H\) in the calculator. Trim the excess at lower sections during install.
Can I mix dye lots?
Avoid mixing. Dye-lot variation is noticeable under daylight. If you must, alternate strips between lots in low-visibility areas and confirm under the room’s lighting first.