Wallpaper Calculator
This wallpaper calculator estimates how many physical rolls to buy from the dimensions on your product label. Enter wall width, height, roll size, and pattern repeat; the tool allows extra length for trimming and counts full strips. The result refers to rolls of the length you enter, whether your supplier calls them single rolls, double rolls, or bolts.
Wallpaper rolls needed
9rolls
- Strips to hang26
- Cut length per strip (drop)8' 4"
- Usable drops per roll3
- Spare strips — your waste allowance1
Updated .
How wallpaper strips become rolls to buy
The calculation works in full-height strips. Area alone misses the length left at the end of each roll: two short offcuts cannot form one seamless strip.
drop = ceil(cut height ÷ repeat) × repeat
strips = ceil(total wall width ÷ roll width)
drops per roll = floor(roll length ÷ drop)
rolls to buy = ceil(strips ÷ drops per roll)
For paper with no repeat, the drop equals cut height. For a straight-match pattern, it rounds up to a whole number of repeats. Measure the tallest point of the wall and keep a trimming allowance for uneven ceilings and baseboards. The default adds 4 inches in total; adjust it to the hanging instructions supplied with your paper.
The result counts physical rolls of the entered length. A 20.5-inch-wide roll that is 33 feet long is sold by some US brands as a double roll. If that is the length entered here, buy the displayed number of those double rolls. Do not divide the result by two. A pricing unit called a “single roll” is not enough information to determine the usable length.
This tool models plain and straight-match paper. Half-drop, offset-match, reverse-hang, and mural layouts can have different cutting rules. Use the product instructions or ask the installer to verify those layouts. No area is deducted for openings because the strips may still need matching above and below them.
Worked example: wallpaper for a 12 × 10 ft dining room
The defaults describe 8-foot walls, plain paper, a 20.5-inch-wide roll that is 33 feet long, and 4 inches of total trimming allowance per strip.
- Perimeter: 2 × (12 + 10) = 44 ft, or 528 inches.
- Strips: ceil(528 ÷ 20.5) = 26 strips.
- Cut length: 96 inches of wall + 4 inches of trim = 100 inches.
- Drops per roll: floor(396 ÷ 100) = 3 full drops.
- Buy: ceil(26 ÷ 3) = 9 rolls, each 33 feet long.
Nine rolls provide 27 full drops, leaving one spare strip. If the store calls a 33-foot package a double roll, this order is nine double-roll packages. The offcut from each roll is shorter than a full drop; use it only where the layout and pattern allow. Reducing trim to zero would give seven rolls on paper, but that assumes perfectly sized walls and cuts with no trimming margin.
Wallpaper rolls for common room sizes
Counts below use 8-foot walls, 20.5-inch × 33-foot physical rolls, and 4 inches of total trim per strip. Plain drops are 100 inches; 12-inch repeats produce 108-inch drops and 24-inch repeats produce 120-inch drops.
| Room size | Perimeter | Plain | 12″ repeat | 24″ repeat |
|---|---|---|---|---|
| 8 × 10 ft | 36 ft | 8 | 8 | 8 |
| 10 × 10 ft | 40 ft | 8 | 8 | 8 |
| 10 × 12 ft | 44 ft | 9 | 9 | 9 |
| 12 × 12 ft | 48 ft | 10 | 10 | 10 |
| 12 × 14 ft | 52 ft | 11 | 11 | 11 |
| 14 × 16 ft | 60 ft | 12 | 12 | 12 |
| 16 × 20 ft | 72 ft | 15 | 15 | 15 |
All three columns match here because each cut length still yields three strips per roll. Different wall heights or repeat lengths can cross a full-strip boundary and change the order sharply. Measure your actual room instead of treating the chart as a universal coverage label.
Frequently asked questions
Does this result mean single rolls or double rolls?
It means physical rolls of the width and length you entered. For example, if the label says 20.5 inches × 33 feet and the result is nine, buy nine packages of that size. Some stores call that package a double roll and quote a price per single roll. Match the dimensions and the checkout package quantity, rather than halving the calculator result.
Why does adding a few inches of trim change my wallpaper order?
Only complete drops count. A 33-foot roll contains 396 inches, enough for four 96-inch drops with 12 inches left. Adding four inches to each drop makes them 100 inches long, so only three fit. That changes the default room from seven to nine rolls. Keep the trim your product and wall conditions need instead of reducing it just to lower the estimate.
Can this calculator handle half-drop wallpaper patterns?
The repeat formula assumes a plain or straight-match layout with the same starting point for adjacent drops. Half-drop and offset patterns may need alternating cut lengths or different starting points across rolls. Check the manufacturer’s hanging sequence and have your installer confirm the order. Murals sold as numbered panels also need their own panel-layout calculation.
Should I subtract doors and windows when ordering wallpaper?
Usually start with the full wall widths. A strip crossing an opening may still consume a full drop to preserve alignment above and below it. Wide openings can save material when you prepare a detailed cutting plan, but subtracting their square footage from the room area does not reliably predict whole rolls. The calculator therefore leaves opening deductions out.
How can I avoid a color mismatch when buying extra wallpaper?
Check the batch or dye-lot number on every roll before cutting. Order enough from the same production run, including any extra repair roll you want to keep. The spare-strip line is only the number of unused full drops after the calculated cuts; it does not guarantee an unopened roll for future repairs or cover every hanging mistake.
Sources and assumptions
- York Wallcoverings: Sander Geometric product dimensions — An example of a 20.5-inch × 33-foot package sold as a double roll; other products have different dimensions.
- York Wallcoverings: hanging instructions — Allow extra for trimming and check roll batch numbers. Follow the instructions for your chosen product.
These results are planning estimates only — verify quantities with your supplier and local building code before you buy or build. See our terms of use.