How the calculation works
The formulas
Each wall width rounds up to full drops. All drops use the tallest entered wall. Straight matching rounds the cutting length to a full repeat; half-drop adds a conservative half-repeat to every cutting length.
Drops = Σ ceil(wall width ÷ roll width)
Base cut = tallest wall + total trim
Straight cut = ceil(base cut ÷ repeat) × repeat
Half-drop cut = straight cut + repeat/2
Rolls = ceil(drops ÷ floor(roll length ÷ cut length))
Assumptions to check
- Openings are not deducted, and offcuts are not reused across walls. Trim is the total top-plus-bottom allowance per drop.
- Half-drop is a conservative allowance, not an optimized motif cutting sequence; check the manufacturer’s match instructions.
A worked example
For a 4 m wide, 2.5 m high wall, 0.53 × 10.05 m rolls and 0.1 m trim, free matching gives 8 drops, 3 per roll, and 3 rolls.