How this calculator works
Round wall height plus total trimming up to a whole pattern repeat, then count full drops from one roll. Half-drop mode adds another half-repeat to every strip as a conservative allowance; a planned alternating cut sequence may use less. Count drops on each room wall separately to avoid assuming a strip crosses a corner. Door and window deductions report net area but do not reduce full-height drop count, because offcut reuse depends on their positions.
Formula
adjusted drop = ceil[(height + trim)/repeat] x repeat, or height + trim for no repeat; drops per roll = floor(roll length/adjusted drop); rolls = ceil(total wall drops/drops per roll).
Worked example
A 4 m wall at 2.5 m height needs eight 0.5 m-wide drops. With no trim or repeat, a 10 m roll yields four drops, so two rolls. A 0.6 m repeat raises each cut to 3 m and requires three rolls.
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Frequently asked questions
Why are openings not subtracted from roll count?
Area alone cannot show which full drops are interrupted or whether offcuts fit above and below an opening. Retaining full drops provides a conservative takeoff.
Is the price for a single or double roll?
Enter the actual packaged roll length and its price together. Retail terms such as double roll can otherwise cause a twofold error.
Does half-drop matching always waste this much?
No. Alternating drops and reusing offcuts can improve yield. This mode deliberately allows a half repeat on each strip rather than optimising a cutting sequence.