Understand wallpaper strips, repeat and roll counts
Explain complete strips, roll-start allowance, limited straight match and actual physical roll packaging.
Wallpaper has enough area for a project only if it can supply the required pieces in the required shape. Leftover area that is too short for a full-height strip cannot necessarily cover the next strip. That is why this tool counts full strips rather than simply dividing wall area by roll area.
Count widths wall by wall
For each wall, round wall width ÷ roll width upward. The rectangular-room tool counts two walls of each room dimension separately. It does not assume that the last partial-width piece can wrap around a corner or that two narrow offcuts form a new strip.
Ordinary doors and windows are not deducted in this conservative full-height-strip model. No short offcuts are reused. A product manufacturer's ordering method may differ; compare the assumptions before ordering.
A free-match example
One test wall is 3.2 m wide and 2.4 m high. Paper width is 0.53 m; physical roll length is 10 m.
Full strips = ceil(3.2 ÷ 0.53) = 7.
Total trim entered is 0.1 m, giving 2.5 m cut length.
With zero confirmed start allowance, four complete strips fit in a roll. Two base rolls supply the seven strips.
The current room tool estimates all four walls; this one-wall example explains the arithmetic, not an input shortcut.
Supported straight-match estimate
For straight match, the tool rounds wall height plus trim upward to a whole vertical repeat. A user-confirmed start allowance is deducted from each physical roll before counting strips. Unknown alignment allowance needs confirmation; it is not assumed to be zero.
Using the same one-wall dimensions, a 0.64 m repeat produces 2.56 m cuts. With 0.2 m start allowance, 9.8 m is usable, giving three strips per roll and three base rolls. Spare rolls are a separate entered whole number.
This limited model uses one height per assigned product group. Different heights require separate entries; the tool does not optimise mixed cuts between rolls. Offset, half-drop, quarter-drop and murals are unsupported and block the estimate.
Check the physical unit sold
A single-roll price can refer to a product sold as a double roll or bolt. Enter the actual physical length and width of one purchased unit, and use the price for that same unit. A pricing convention is not a physical measurement.
Plan full wallpaper rolls and verify pattern, batch, product instructions and all allowances before purchasing.
Sources and scope
For definitions of wallpaper match, repeat and packaging, see Brewster's product properties and Graham & Brown's wallpaper FAQ. Product instructions take precedence over generic examples. Unit conversions use the exact international foot (0.3048 m) and US liquid gallon (3.785411784 L); see NIST conversion factors.