Count strips, not only square feet
Roll area alone can hide the waste from full-height drops and matching repeats. This calculator divides each wall width by roll width, rounds up to full strips and fits conservative cut lengths into rolls. It keeps all wallpaper above and below openings in the estimate rather than assuming every offcut is reusable.
Straight and half-drop assumptions
For straight match, wall height plus total trimming is rounded up to a whole repeat. Half-drop adds another half-repeat to every such strip. This deliberately generous method allows alignment but may overbuy compared with a skilled alternating-drop plan. Free match uses height plus trimming with no repeat adjustment. Confirm the hanging sequence with your supplier.
A worked roll estimate
A 120 × 96-inch wall needs six 20.5-inch-wide strips. With 4 inches total trimming and a 21-inch straight repeat, each cut is 105 inches. A 396-inch roll fits three such cuts, so two rolls cover the wall before an optional spare. A half-drop allowance raises each cut to 115.5 inches in this model.
What the roll count means
The planner puts the longest cuts into available rolls first. It is a practical cutting estimate, not proof of the fewest possible rolls. Check whether a product is sold as single rolls, double rolls or panels; enter the physical roll length, not the name on a listing. Use one dye batch and include any manufacturer-specific allowance.
Questions, answered
Are doors and windows deducted?
No. They appear in the shared wall sketch, but the wallpaper cutting plan still allows full-height strips.
Is half-drop exact?
It is a conservative allowance, not an optimized alternating-drop layout. Ask the supplier to confirm the hanging plan.