Wallpaper — planning and calculation
Measurements, rolls, pattern repeat and paste · Step-by-step · NO/EU/US wallpaper formats
Wallpaper is one of the most common ways to refresh a room — it adds texture, pattern and character in a way paint simply cannot. At the same time, it is easy to miscalculate the number of rolls or forget to account for pattern repeat, which means an expensive extra trip to the shop. This guide walks you through everything from understanding roll formats and pattern repeats, to calculating the exact number of rolls and hanging wallpaper correctly.
Wallpaper rolls and sizes
Wallpaper rolls come in different standard sizes depending on country of origin and product type. It is important to know the format you are buying, as this directly affects the calculation.
European standard
- Width: 520 mm — by far the most common width in Norwegian and European stores
- Length: 10 m per roll
- Area per roll: 5.2 m² (gross, before trimming and pattern repeat)
- Wider rolls (700 mm, 750 mm, 900 mm) are used for premium wallpaper collections and result in fewer seams
European standard: 52 cm × 10 m = 5.2 m² per roll. Older Norwegian building catalogues used 53 cm width — always verify the dimensions on the packaging.
Specialist and non-woven wallpaper
- Non-woven / fabric-backed: the most common type today; paste is applied to the wall (not the wallpaper), it does not shrink and is easy to remove
- Paper wallpaper: traditional type; paste is applied to the back of the paper, requires precise work as paper can stretch when wet
- Vinyl and textile wallpaper: durable, washable; suitable for kitchens and children's rooms
- Fibreglass wallpaper: extremely hardwearing, used as a paintable backing on walls with cracks
Pattern repeat (rapport)
The pattern repeat is the vertical distance between two identical points in the design. Wallpapers with a pattern repeat require strips to be aligned side by side so the pattern matches — this produces waste. The larger the repeat, the more waste.
Types of repeat
- No repeat (0 mm): plain colour, stripes or textured wallpaper — no extra waste
- Straight match: the pattern starts at the same height on every strip — easy to hang, low waste
- Half-drop match: every other strip is shifted down by half the repeat length — typically 15–25% extra waste per roll
- Random match: textures and rough structures with no repeating pattern — no extra waste
Example: A wallpaper with a 640 mm repeat (large floral design) and a 2.4 m room height: effective strip length = ⌈(2,400 + 640) ÷ 640⌉ × 640 = 5 × 640 = 3,200 mm per strip — you use 3,200 mm of roll per strip instead of 2,400 mm. This results in approximately 33% more material.
Calculating the number of rolls
The calculation is done in four steps:
- Perimeter: measure the total wall width around the room (all four walls). Subtract the widths of doors (typically 0.9 m) and windows (typically 1.2 m per window).
- Strips: Number of strips = ⌈perimeter ÷ roll width⌉ — always round up.
- Strip length with repeat: Strip length = ⌈room height ÷ repeat⌉ × repeat. Add 50 mm safety margin for top and bottom trimming.
- Rolls: Rolls = ⌈(strips × strip length) ÷ roll length⌉ + 1 (extra for reserve and off-cuts)
Rolls = ⌈(⌈perimeter ÷ roll width⌉ × strip length) ÷ roll length⌉ + 1
Example: Room 3.5 m × 4.0 m, height 2.4 m, one door 0.9 m, one balcony door 1.8 m, repeat 320 mm, European roll (520 mm × 10 m):
- Perimeter: (3.5 + 4.0 + 3.5 + 4.0) m − 0.9 m − 1.8 m = 13.3 m
- Strips: ⌈13.3 ÷ 0.52⌉ = ⌈25.6⌉ = 26 strips
- Strip length: ⌈2,400 ÷ 320⌉ × 320 = 8 × 320 = 2,560 mm + 50 mm = 2,610 mm
- Rolls: ⌈(26 × 2.61) ÷ 10⌉ + 1 = ⌈6.79⌉ + 1 = 7 + 1 = 8 rolls
Step-by-step guide
Step 1 — Measure the room
- Measure the length, width and height of each room
- Measure all doors and windows precisely — both width and height
- Note the pattern repeat from the wallpaper packaging (the symbol looks like two overlapping arrows)
- Check that all walls are plumb — out-of-plumb walls require extra adjustment
Step 2 — Choose wallpaper and find the repeat
- Choose wallpaper type for the room: non-woven is the easiest to hang and remove
- Check the repeat on the packaging — the symbol for straight match is ↔, half-drop is ↕
- Buy all rolls from the same batch number (dye lot) — colour can vary between production batches
Step 3 — Prepare the wall
- Remove old wallpaper; soak paper wallpaper with warm water and wallpaper remover, steam is even more effective
- Fill cracks and holes with filler; allow to dry and sand lightly
- Prime new plasterboard walls and highly absorbent surfaces — otherwise the wall draws paste out of the wallpaper too quickly
- Clean, painted walls can be papered directly, but light sanding improves adhesion
Step 4 — Cut strips
- Cut all strips to the calculated strip length plus 50 mm safety margin
- Lay strips out and verify the pattern aligns between strip 1 and 2, 2 and 3, etc. before cutting
- Number strips on the back to keep track of the order
Step 5 — Apply paste
- Non-woven: apply paste to the wall with a paste roller or wide brush — this is the recommended method
- Paper wallpaper: apply paste to the back of the paper with a paste brush; fold the paper (paste to paste) and allow to rest 3–5 minutes so the paper absorbs the paste evenly
- Use the correct paste strength: light paste for paper wallpaper, heavy-duty paste (with additive if needed) for heavy non-woven and vinyl types
Step 6 — Hang the first strip against a plumb line
- Draw a vertical plumb line on the wall using a plumb bob or laser level — walls and door frames are rarely truly plumb
- Start at a corner (but always against the plumb line) or a central focal point for feature wallpaper
- Hang the wallpaper from the top, leaving 20–30 mm overlapping the ceiling cornice for trimming
- Smooth out with a wallpaper brush or smoother, working from the centre outward — remove all air bubbles
- Trim excess at ceiling and floor with a wallpaper knife against a straight edge after the paste has set slightly (10–15 min.)
Tips: Never hang two strips into an internal corner as a single wide strip. Instead, cut the strip so it is approximately 20 mm wider than the distance to the corner, fold it around, and start the next strip with a fresh plumb line. This always gives straight strips, even if the corner is slightly out of square.
Formats and practical notes
Wallpaper is an interior finish product. Practical considerations when choosing and calculating:
- NO/EU: European standard roll format 52 cm × 10 m, repeat and matching symbols follow manufacturer conventions — check the product datasheet
- US: 27" (68.6 cm) × 33 ft (10 m), sometimes sold as a "double roll" (20 m). Calculation in ft² is common: 1 roll covers approx. 30–35 ft²
- In corridors and stairwells, local fire regulations may apply to surface finishes — check the product datasheet and local rules if in doubt
Reference table
| Parameter | Value |
|---|---|
| EU standard roll | 520 mm × 10 m = 5.2 m² |
| US standard roll | 27" (686 mm) × 33 ft ≈ 6.5 m² |
| Typical repeat, decorative | 320–640 mm (check packaging) |
| Extra waste, half-drop repeat | 15–30% extra rolls |
| Recommended safety margin | 1 extra roll (minimum) |
| Paste soak time, paper wallpaper | 3–5 min. after applying paste to back |
| Drying time, paste (non-woven) | 24–48 hours |
| Hanging direction | From plumb line, typically right to left |
| Cutting tool | Wallpaper knife and straight edge (not scissors) |
| Fire class, escape routes | Check local fire class requirements for escape routes |
Common mistakes
- ✗Not buying enough from the same batch number — colour shade varies between production batches
- ✗Ignoring the pattern repeat in the calculation — a large repeat (64 cm+) can produce 30–40% extra waste per drop
- ✗Starting from a door corner instead of a prominent wall — any misalignment shows most at the room's entrance
- ✗Hanging on an unprimed wall — bare plasterboard and filler absorb paste unevenly and the wallpaper loses adhesion
- ✗Hanging wet wallpaper too tight — the paper shrinks slightly as the paste dries and overstretched edges lift or crack
- ✗Missing that the repeat is a half-drop — you calculate the wrong number of drops and run short
- ✗Not removing old wallpaper properly — trapped air and old paste underneath causes bubbles to appear after drying
Calculate your rolls
Use the wallpaper calculator for automatic calculation with pattern repeat:
Wallpaper calculator
Number of rolls, pattern repeat and cost based on room dimensions and wallpaper type
Paint calculator
Calculate primer and undercoat for walls to be wallpapered
Frequently asked questions
What is a pattern repeat and why does it matter?
Pattern repeat is the length of one full pattern motif. Large repeats (>24") create more waste per strip as each new strip must be aligned. Always add extra rolls for large repeats.
What is the standard width of wallpaper?
US wallpaper rolls are typically 27" wide, but Euro rolls (common in many stores) are 20.5" wide. Check the roll specs carefully before calculating.
Should I wallpaper the ceiling or walls first?
Always paper the ceiling first to avoid drips ruining finished walls. Work top to bottom and leave trimming corners and edges until last.
References
- → Graham & Brown — How to hang wallpaper
- → Cole & Son — Wallpaper technical information and hanging guide
- → Brewster Wallcovering — installation guide for non-woven wallpaper
- → Local building regulations — fire reaction class requirements for surface finishes in escape routes
Calculations are indicative. Always check the pattern repeat and roll dimensions on the specific wallpaper packaging — these vary between manufacturers and product ranges. Always buy a little extra from the same batch number. Last reviewed: May 2026