Wallpaper Roll Calculator

If you’ve ever stood in a home décor store staring at rolls of wallpaper, wondering, “How many do I actually need?”, you’re not alone. Buying too little can stop your project halfway. Buying too much wastes money. That’s why we created this Wallpaper Roll Calculator — so you can get it right every time.

Whether your room is 12x12 feet, has pattern repeats, or you’re working in square feet, inches, or meters, this tool does the math for you in seconds.

Why You Need a Wallpaper Calculator

Measuring walls is easy. But wallpaper math can be tricky. You need to factor in the wall height, the total width, the roll size, and any pattern repeat. Even a small mistake can throw off the whole job.

Our calculator is built for real-world use. It works with metric and imperial units, so whether you think in feet or meters, you’re covered. You can even add a trim allowance for cutting and a contingency percentage for safety.

How to Use the Wallpaper Roll Calculator

1. Measure the wall height from floor to ceiling.
2. Measure the total wall width you want to cover (subtract doors and windows).
3. Enter the roll width and roll length (check your wallpaper label).
4. Add the pattern repeat if there is one.
5. Add a trim allowance (about 10 cm or 4 inches is standard).
6. Choose your contingency (we suggest 10–15% extra).
7. Click calculate — you’ll get exact rolls needed and a recommended amount.

The Calculation Formula

Our tool uses the standard wallpaper formula used by decorators worldwide:

H_trim = wall_height + trim_allowance

drop_length = (pattern_repeat > 0)  ? ceil(H_trim / pattern_repeat) * pattern_repeat   : H_trim

drops_per_roll = floor(roll_length / drop_length)

total_drops = ceil(total_wall_width / roll_width)

exact_rolls = ceil(total_drops / drops_per_roll)

recommended_rolls = ceil(exact_rolls * (1 + contingency_percentage))

This formula ensures your pattern lines up perfectly and you have enough material for mistakes or cuts.

Example: 12x12 ft Room with 30 cm Pattern Repeat

Let’s say your room is 12 feet by 12 feet, wall height 8 feet, roll width 20.5 inches, roll length 33 feet, pattern repeat 12 inches, trim allowance 4 inches, and contingency 10%.

• H_trim = 8 ft + 0.33 ft = 8.33 ft
• Drop length = Round up to nearest 1 ft pattern = 9 ft
• Drops per roll = floor(33 / 9) = 3 drops
• Total drops = ceil(48 ft total width / 1.71 ft roll width) = 29 drops
• Exact rolls = ceil(29 / 3) = 10 rolls
• Recommended rolls = ceil(10 × 1.10) = 11 rolls

You’d buy 11 rolls to be safe.

Final Verdict

A Wallpaper Roll Calculator saves time, money, and stress. It turns messy math into a clean answer in seconds. Whether you’re covering a single accent wall or an entire room with a tricky pattern, you’ll know exactly what to buy — and you won’t be left short halfway through your project.

FAQs

How much will a 10m roll of wallpaper cover?

A standard 10m × 53cm roll covers about 5.3 m², but the exact coverage depends on wall height and pattern repeat.

How do I calculate rolls for a pattern repeat?

Increase each drop length to the next full repeat above your wall height + trim, then recalculate drops per roll.

Can I use the calculator for inches or square feet?

Yes, our tool supports feet, inches, meters, and centimeters.

How many lengths do you get from a roll?

Divide the roll length by your adjusted drop length (including pattern repeat and trim).