How to Calculate Wallpaper: Complete Guide

Ordering wallpaper can be stressful. Order too few rolls and you're stuck with mismatched patterns from a different batch. Order too many and you've wasted money on rolls you'll never use.

The good news? Calculating wallpaper accurately is simple once you understand the formula. This guide walks you through every step, from measuring your walls to accounting for pattern repeats and waste.

The Basics: What You Need to Know

Before you start calculating, you need three key measurements from your wallpaper packaging:

• Roll length: Usually 10 meters (33 feet) in Europe, 10.05 meters in North America
• Roll width: Typically 53cm (21 inches), though some designer papers are 68cm or 90cm wide
• Pattern repeat: How often the pattern repeats vertically (we'll cover this in detail below)

You'll also need to measure your room:

• Wall height: Floor to ceiling measurement
• Room perimeter: Total length of all walls you're papering
• Openings: Doors and windows (though it's often safer to ignore these for waste allowance)

The Calculation Formula

Here's the basic formula for calculating wallpaper rolls:

1. Calculate strips needed: Room perimeter ÷ Roll width = Number of strips
2. Calculate usable length per roll: Roll length ÷ (Wall height + Pattern repeat) = Strips per roll
3. Calculate rolls needed: Strips needed ÷ Strips per roll = Total rolls

Example Calculation

Let's say you have a room with:

• Perimeter: 16 meters
• Height: 2.4 meters
• Roll width: 0.53 meters
• Roll length: 10 meters
• Pattern repeat: 0.32 meters

Step 1: Strips needed = 16 ÷ 0.53 = 30.2 strips (round up to 31)

Step 2: Usable length = 2.4 + 0.32 = 2.72 meters per strip

Step 3: Strips per roll = 10 ÷ 2.72 = 3.67 (round down to 3 full strips)

Step 4: Rolls needed = 31 ÷ 3 = 10.3 rolls (round up to 11 rolls)

Understanding Pattern Repeat

Pattern repeat is where most DIY mistakes happen. Here's what you need to know:

What is Pattern Repeat?

Pattern repeat is the vertical distance before the design repeats itself. It's always printed on the wallpaper label, usually in centimeters.

For example, if a pattern has a 32cm repeat, every 32cm up the wall the pattern starts over. This matters because you need to match patterns across strips—meaning you'll waste some paper at the top or bottom of each strip.

Types of Pattern Repeat

• No repeat / Random match: Plain colors or textures with no pattern to match. Minimal waste.
• Straight match: Pattern aligns horizontally across strips. Moderate waste (add full pattern repeat to wall height).
• Drop match / Offset match: Pattern alternates every other strip. Higher waste (add 1.5× the pattern repeat).

Adding Waste Allowance

Even with perfect calculations, you should order extra rolls for:

• Cutting mistakes: Everyone makes at least one bad cut
• Damage during hanging: Tears, creases, or paste mistakes
• Future repairs: It's nearly impossible to match wallpaper from different batches
• Complex layouts: Corners, alcoves, and odd spaces create extra waste

How Much Extra to Order

Add these safety margins to your final roll count:

• Simple rooms: +1 roll (straight walls, minimal openings)
• Standard rooms: +2 rolls (normal layout with doors/windows)
• Complex rooms: +3 rolls (lots of corners, alcoves, or sloped ceilings)
• Large patterns (60cm+ repeat): Always add +2 extra rolls regardless of room complexity

Common Mistakes to Avoid

1. Measuring Only One Wall Height

Older homes rarely have level ceilings. Always measure the tallest point and use that for all calculations.

2. Forgetting to Check Batch Numbers

Even the "same" wallpaper can vary slightly between production batches. The difference might not be obvious in the store, but it'll stand out on your wall. Always check that all rolls have the same batch number printed on the label.

3. Ignoring the Pattern Direction

Some patterns have a "this way up" direction. Hanging them upside down might seem fine until the light hits them wrong. Check the label or packaging for arrows.

4. Not Accounting for Large Openings

While it's often recommended to calculate as if doors and windows don't exist (for waste allowance), if you have very large openings like patio doors or picture windows, you might safely subtract 1-2 rolls from your final count.

5. Assuming All Rolls Are Created Equal

European rolls (10m × 53cm) and American rolls (10.05m × 52-53cm) are slightly different. If you're buying internationally, double-check the specifications.

Conclusion

Calculating wallpaper doesn't have to be complicated. The key is to:

• Measure carefully (wall height and room perimeter)
• Add the pattern repeat to your wall height
• Round up at every step to avoid shortages
• Add 1-3 extra rolls for waste and future repairs
• Verify all rolls have the same batch number

With these guidelines, you'll order exactly what you need—no more disappointing trips back to the store mid-project.

Ready to calculate your wallpaper needs? Try our free wallpaper calculator to get accurate results in seconds, complete with pattern repeat and waste calculations.