Wallpaper Calculator

Ordering the right number of wallpaper rolls is trickier than it sounds. Buy too few and you risk a dye-lot mismatch when you reorder. Buy too many and you waste money on rolls that sit in a cupboard forever. This wallpaper calculator handles all the math — room dimensions, doors and windows, roll size, and pattern repeat — so you know exactly how many rolls to add to your cart before you start.

Step 1: Enter Your Room Dimensions

Measure the length, width, and ceiling height of the room you plan to wallpaper. The calculator computes the total wall area by multiplying the room's perimeter (2 × length + 2 × width) by the wall height. If you prefer metric, click the "Metric" toggle at the top — all inputs and labels switch to meters and centimeters automatically.

Step 2: Account for Doors and Windows

Enter the number of doors and windows in the room. Each door deducts approximately 21 square feet (3 ft × 7 ft) and each window deducts approximately 12 square feet (3 ft × 4 ft) from the total wall area. This gives you the net paperable area — the surface you actually need to cover — and prevents you from buying rolls for space that will not be papered. In a typical room with one door and two windows, this can save one or two rolls.

Step 3: Select Your Roll Size

Choose one of the preset roll sizes — US Standard (20.5" × 33ft), Wide (27" × 33ft), or European (20.5" × 16.5ft) — or click Custom to enter any roll dimensions. The calculator uses the roll width and roll length to determine how many usable strips each roll contains and the coverage area per roll. Always verify the exact roll dimensions on the product label or supplier website, as sizes can vary slightly by brand.

Step 4: Enter the Pattern Repeat (If Any)

The pattern repeat is the vertical distance over which the wallpaper design completes one full cycle. For solid or textured wallpapers with no pattern, leave this at 0. For patterned wallpapers, the repeat is printed on the label — common values are 12, 18, or 24 inches. When a pattern repeat is set, the wallpaper calculator adds the repeat distance to the effective strip length needed, increasing waste but ensuring a clean pattern match across all strips. A larger repeat on a short wall height significantly increases the number of rolls required.

Step 5: Review Results and Add Pricing

The results section shows four key figures: total wall area, net area after subtracting openings, rolls needed (always rounded up to the nearest whole roll), and estimated cost. Optionally enter a price per roll to see the total material cost. The detailed breakdown below shows how the roll count was calculated, including strips per roll, coverage per roll, and pattern waste percentage — so you can verify the estimate and adjust inputs if needed.

Pro Tip: Always Buy One Extra Roll

Even after the calculator gives you an accurate count, professionals recommend buying one extra roll from the same dye lot (the batch number printed on the label). Wallpaper colors vary slightly between production runs, and a replacement roll purchased months or years later may not match perfectly. Keeping a spare roll ensures you can patch any damage or future wear without a noticeable color difference.