Wallpaper Calculator
Calculate how many rolls of wallpaper you need for a room, including doors, windows, and waste factor.
Wallpaper is one of those materials where running short is significantly more painful than paint, you can't always buy from the same dye lot later. I add a full roll buffer beyond the calculated amount for any patterned wallpaper. A leftover roll stores flat in a closet for years; an unfinished wall or mismatched patch lasts longer.
Always buy one extra roll and keep it sealed. Wallpaper dye lots vary between manufacturing runs. A roll from the same SKU purchased later may not match the original installation, and you won't know until you're hanging it.
How wallpaper is sold
US double rolls cover approximately 56–57 sq ft but are sold as single rolls at that price. Confusingly, many US retailers label them as single rolls. European rolls (typically 27" wide × 33 ft long) cover about 58 sq ft. Always check the actual square footage listed on the bolt, not the roll count. This calculator uses the roll coverage you enter, so input the actual sq ft per unit you're buying.
Pattern repeat and waste
Patterned wallpaper requires strips to be aligned at the repeat point, which wastes material at the top and bottom of each strip. A 12-inch repeat means each strip may waste up to 12 inches of material for alignment. Larger repeats waste more, a 24-inch repeat on a 9-foot wall can waste 2 feet per strip. This calculator adds waste proportional to the repeat size.
Ceiling coverage
This calculator covers walls only. Wallpapering a ceiling (becoming more common for statement ceilings) requires a separate calculation: ceiling area ÷ roll coverage, with a higher waste factor because strips run across the ceiling and must be measured from the longest dimension.
Frequently asked questions
How do I measure wall area with an irregular room?
Measure the perimeter of the room (sum of all wall widths) and multiply by ceiling height. Subtract standard deductions for doors (21 sq ft each) and windows (15 sq ft each). This calculator does this automatically from the length, width, and window/door inputs.
Can I hang wallpaper over existing wallpaper?
In some cases, but it's generally not recommended. Old wallpaper can bubble and peel, especially at seams, taking the new paper with it. The additional weight and moisture during application can loosen older paper. Stripping to bare drywall (or skim coating bare drywall) before hanging produces the best long-term result.
What's the difference between pre-pasted and paste-the-wall wallpaper?
Pre-pasted paper has adhesive on the back that activates with water. Paste-the-wall paper requires applying wallpaper paste to the wall, not the paper, newer nonwoven papers often use this method and offer easier installation and removal. Traditional paper-backed wallpaper requires pasting the back of the paper and allowing it to relax (book) before hanging.