Before buying wallpaper, it’s very important to calculate how much you need correctly.
By following the steps below, you can easily avoid:
- Buying too little and running out halfway
- Buying too much and wasting money
Step 1: Check Key Product Information (Before You Measure!)
This step is crucial – it directly affects waste and the final number of rolls you need.
Please check the product page and confirm:
1. Roll size (length × width)
2. Pattern type:
- No pattern match: plain or random design
- Straight match: the pattern must line up between adjacent strips
⚠️ Note: If the wallpaper has any pattern that needs aligning, you must allow extra length for matching.
Step 2: Prepare Your Tools & Draw a Simple Sketch
You will need:
- Tape measure
- Paper & pen
- Calculator
What to do:
- Draw a simple outline of the room walls
- Mark the positions of doors, windows, cupboards, fireplaces, etc.
It doesn’t need to look professional — just clear enough for you to understand each wall area.
Step 3: Measure the Wall Height (This Determines the Length of Each Drop)
1. Measure from the top of the skirting board to the ceiling
2. Add 10 cm for trimming at the top and bottom
3. If your wallpaper has a pattern, add another 20 cm for pattern matching
Formula:
- No pattern match: Drop length = Wall height + 10 cm
- With pattern match: Drop length = Wall height + 10 cm + 20 cm
This step is the main source of wallpaper waste.
Step 4: Calculate How Many Drops You Need in Total
1. Measure the width of each wall
2. Add up the widths of all walls you want to cover
3. Use this formula:
Total drops = Total wall width ÷ Wallpaper roll width
Always round up to the next whole number.
Example:
- Total wall width = 10 m
- Wallpaper width = 0.53 m
- 10 ÷ 0.53 ≈ 18.87 → You need 19 drops
Step 5: Calculate How Many Drops One Roll Can Provide
Use this formula:
Drops per roll = Roll length ÷ Drop length
Always round down.
Example:
- Roll length = 9 m
- Each drop length = 2.5 m
- 9 ÷ 2.5 = 3.6 → You can get 3 full drops from one roll
❓ Why Round Down? Why Can’t the Remaining 0.6 Strips Be Used as One Whole Strip?
Although it may seem possible to join two pieces together, in real installations this would create a horizontal joint in the middle of the wall, which:
- Is very visible
- Can open or peel over time
- Looks unprofessional and ruins the finish
Industry standard practice:
- Each drop must be cut from one single continuous piece, from ceiling to floor.
The leftover pieces can only be used:
- Above doors or windows
- For small repairs
They cannot be counted as a full usable drop.
Step 6: Calculate How Many Rolls You Need
Number of rolls = Total drops ÷ Drops per roll
Always round up.
Example:
- You need 19 drops
- Each roll gives 3 drops
- 19 ÷ 3 ≈ 6.33 → You must buy 7 rolls
✅ Summary: Your Action Checklist
1. Check wallpaper size and pattern type
2. Measure wall height and calculate drop length (including waste)
3. Measure total wall width and calculate total drops needed
4. Calculate how many drops one roll can provide
5. Calculate total rolls needed (always round up)
FAQs
Q1: More than one room?
A1: Calculate each room separately.
Q2: Lots of doors and windows?
A2: Do not subtract them — trimming will use the material anyway.
Q3: Only doing one feature wall?
A3: Only calculate that wall.
Q4: Different ceiling heights?
A4: Always use the tallest wall.
Final Tip
By following this guide, you’ll minimise waste and make sure you have enough wallpaper to finish the job properly.
Happy decorating! 🎨
