Wallpaper Calculator

1. Choose Unit system, then select Imperial (ft / in) or Metric (m / cm).
2. Enter Total wall width as the combined width of the walls you plan to paper, and enter Wall height.
3. Enter Number of doors, Average door width, Number of windows, Average window width, Roll width, Roll length, Pattern repeat, and Waste / overage %.
4. Select Calculate to show the estimate. Use Copy result or Download result (.txt) to keep the plain-text result.
5. Select Reset to clear the wall dimensions, restore Imperial defaults, clear errors, and hide the result.

Wallpaper roll estimate formula

The calculator treats the wall measurement as a linear width. It subtracts the opening deductions, rounds strips up, applies the waste percentage, and divides the result by the usable drops on one roll.

40 ft wall width, 8 ft height
20.5 in x 33 ft roll, no repeat, 10% waste
= 9 rolls to buy

• When Pattern repeat is above 0, Drop length = Wall height + Pattern repeat.
• At 0, the calculator adds a 4 in trim allowance in Imperial mode or 10 cm in Metric mode.
• Drops per roll = floor(Roll length / Drop length) and Strips needed = ceil(Net wall width / Roll width).
• Rolls to buy = ceil(Strips with waste / Drops per roll).

Wallpaper coverage inputs and unit changes

Use Total wall width for the combined width of the walls being papered. Measure around the room rather than calculating wall area. If the width already excludes openings, set Number of doors and Number of windows to 0.

• Imperial uses feet for wall width, wall height, and roll length. Roll width, pattern repeat, and opening widths use inches.
• Metric uses meters for wall width, wall height, and roll length. Roll width, pattern repeat, and opening widths use centimeters.
• Changing Unit system resets roll width, roll length, pattern repeat, and the default opening widths.
• The count fields step by whole numbers. The script accepts decimal entries and displays those counts rounded to zero places.

Wallpaper calculator limits

The script checks numeric ranges: wall width 1-1,000, wall height 1-100, waste 0-50%, opening counts 0-200, opening widths 0-200, roll width 1-200, roll length 1-500, and pattern repeat 0-200 in the selected units. Door and window deductions cannot equal or exceed wall width. Drop length cannot exceed roll length.

• The calculation uses straight, full-height drops in one continuous run.
• It accepts one wall width and one wall height, so separate sections with different heights or pattern repeats are not calculated separately.
• There are no inputs for chimneys, alcoves, sloped ceilings, pricing, supplier data, brand-specific hanging instructions, or decorating advice.

Where a wallpaper roll estimate comes up

For one feature wall, enter its width and height with the roll dimensions and pattern repeat. The result gives the roll count for that wall.

For a room, add the wall widths together before entering the total. Door and window counts then reduce the width used for the estimate.

Patterned paper changes the drop length before the calculator counts drops on each roll.

When another construction calculator fits better

Use the Paint Calculator for paint quantity based on surface area, coats, coverage, doors, and windows. Choose the Drywall Calculator for sheet counts based on wall or ceiling area, sheet size, and waste. Use the Flooring Calculator for floor area, plank or tile box coverage, roll size, and waste. The Construction Calculators page lists other material, dimension, load, and water-volume estimates.

Frequently asked questions