Measure curtain width, drop and packs
Measure the usable pole or track and the hanging drop, then check whether a product’s stated width is flat fabric or finished coverage. That distinction drives the panel count.
Back to calculator ↑Measure usable span and drop
For an installed pole or track, measure the usable travel span in centimetres and exclude decorative finials. If starting from window width, add the planned extension on each side; the tool forms planned span as window width + 2 × extension. Recheck the actual installed width before ordering.
Measure drop from the actual hanging point to the desired hem. Eyelets, rings, hooks and tracks can start at different heights. Follow the product’s measuring instructions rather than assuming every curtain starts at the top of the pole.
Flat width versus finished coverage
If listed panel width is flat fabric before gathering, the engine multiplies span by your chosen fullness and divides by width per panel. The starting 2× is editable, not a requirement for every fabric. If the listing gives finished pleated coverage, select finished width: the engine uses the span directly and does not apply fullness again.
For a 240 cm pole, flat panels 140 cm wide and 2× fullness, needed fabric width is 240 × 2 = 480 cm. ceil(480 ÷ 140) gives four panels. If sold as two-panel packs, buy two packs. The same listed width interpreted as finished coverage would give a different answer.
Balance panels and count packs
If you select a balanced opening, the engine rounds the planned panel count to an even number before counting packs. For example, a three-panel minimum becomes a four-panel plan. Pack rounding may add more panels when sold as pairs; check the result’s purchased count separately from the planned count.
An optional price per pack gives a curtain-only subtotal. Confirm whether the seller ships one panel or a pair per pack and whether the heading fits your pole or track. Tiebacks, hooks, rails, hemming and fitting are outside that simple price.
Length is a comparison, not a cutting instruction
The tool subtracts desired drop from the listed panel length. A 250 cm curtain against a 240 cm desired drop is 10 cm longer. A short curtain may miss the chosen hem; a long one may allow hemming or a revised hanging position. The difference is a comparison, not an instruction to cut exactly that much.
Check expected shrinkage, drape, heading and intended distance from the floor with the specific product. Measure after installing the hardware when possible, then confirm alterations before paying for made-to-measure or ready-made panels.
Common questions
Should finials count in pole width?
No. Measure the usable span where the curtain can travel.
Should finished pleated width be multiplied by fullness?
No. Select finished coverage so fullness is not counted twice.
Should I cut 10 cm off a panel that is 10 cm long?
First verify hanging point, shrinkage and hemming method.
Sources and calculation guidance
Check these against your chosen product’s label and instructions.