Wallpaper Calculator

How to use this wallpaper calculator

What this calculator does

This calculator estimates the wall area that must be covered, adjusts that requirement for a vertical pattern repeat, rounds the purchase quantity up to whole wallpaper rolls, and multiplies the roll count by the entered price. It is useful for planning a rectangular room, comparing two wallpaper products with different roll dimensions, checking the cost effect of a large repeat, or estimating a project after subtracting standard doors and windows. It is a material-planning estimate rather than an installation guarantee: unusual alcoves, sloped ceilings, half-drop matching, damaged walls, and installer-specific waste may require additional rolls.

How to calculate

1. The calculator opens with a complete demonstration: a 5 m by 4 m room, 2.6 m high, with one door, two windows, a 10.05 m by 0.53 m roll, a 0.64 m repeat, and a price of $45 per roll. The live results and example Excel workbook are immediately available.
2. Replace the room dimensions with measured finished-wall dimensions. Measure the tallest wall height where floors or ceilings vary.
3. Enter the number and size of repeated door and window openings. Use zero counts when you prefer a conservative estimate that does not subtract openings.
4. Copy the roll length, roll width, pattern repeat, and price from the product label or supplier listing. Enter a pattern repeat of 0 for a no-repeat or random-match paper.
5. Read the whole-roll result first, then inspect adjusted height, net wall area, adjusted room area, and total cost. Use the breakdown table to see each calculation stage.
6. Select Download Excel to save the current inputs and results as a validated .xlsx workbook. Reset clears all demonstration values and results; Download Excel then remains unavailable until every required field contains a valid value again.

Input guide

Room length, Room width, and Room height are required positive decimal measurements in meters. Examples are 5, 4, and 2.6. Length and width determine perimeter, while height determines gross wall area and the base drop length. Do not enter floor area in either length field. Number of doors and Number of windows are required whole numbers from 0 to 1,000. Their matching width and height fields are required nonnegative meter values; the sample door is 0.9 m × 2.1 m and each sample window is 1.2 m × 1.4 m. Opening area cannot exceed gross wall area.

Roll length and Roll width are required positive meter measurements from the actual package; the demonstration uses the common 10.05 m × 0.53 m size. Wider or longer rolls increase coverage and can reduce the roll count. Pattern repeat is a required nonnegative vertical distance in meters. A larger repeat can increase the adjusted drop height and material requirement; 0 means no repeat adjustment. The Wallcoverings Association overview of wallcovering helps explain product terminology and selection. Price per roll is a required nonnegative U.S.-dollar amount such as 45; it changes cost only, not quantity.

Output guide

Number of rolls is the purchase quantity rounded up to a whole roll. Adjusted height is the room height rounded up to the next complete pattern repeat; it equals room height when repeat is zero. Net wall area is gross wall area minus doors and windows. Adjusted room area scales that net area by adjusted height divided by room height. Total cost is whole rolls multiplied by price per roll. The summary pills repeat the most important quantity, adjusted area, and cost. In the breakdown table, Gross wall area, Openings area, Roll coverage, and Whole rolls expose the intermediate values used by the estimate.

Worked example

For the startup room, perimeter is 2 × (5 + 4) = 18 m and gross wall area is 18 × 2.6 = 46.80 m². One 0.9 m × 2.1 m door removes 1.89 m², and two 1.2 m × 1.4 m windows remove 3.36 m², leaving 41.55 m². With a 0.64 m repeat, the 2.6 m wall height rounds up to 3.20 m. The adjusted room area is 41.55 × 3.20 ÷ 2.60 = 51.14 m². Each roll covers 10.05 × 0.53 = 5.3265 m², so 51.14 ÷ 5.3265 = 9.60 and the purchase requirement rounds up to 10 rolls. At $45 each, the estimated material cost is $450.00.

Measurement and ordering notes

Measure each wall rather than relying on nominal room dimensions, and use the largest height for uneven surfaces. The U.S. National Institute of Standards and Technology provides a practical SI length measurement reference for consistent meter-based inputs. Product labels remain the best source for roll dimensions and repeat. Many installers avoid subtracting small openings because offcuts around them are not always reusable. For patterned papers, consider an extra allowance for trimming and matching; the Wallcoverings Association residential guidance offers broader planning context. Order all rolls from the same production batch where color consistency matters.

Formula used

Gross area = 2 × (length + width) × height. Net area = gross area – door area – window area. Adjusted height = height when repeat is 0; otherwise ceil(height ÷ repeat) × repeat. Adjusted area = net area × adjusted height ÷ height. Rolls = ceil(adjusted area ÷ (roll length × roll width)). Total cost = rolls × price per roll.