Why a fabric estimate needs more than window width
Curtain fabric requirements depend on finished width, length, heading construction, panel opening and the usable dimensions of the selected fabric. A single width multiplier cannot account for every combination.
The calculator therefore keeps the measurement result separate from the fabric estimate. First it confirms the recommended curtain size; then the selected curtain and fabric supply the remaining production inputs.
An estimate is not a cutting instruction
Pattern repeats, joins, hems and production allowances can change final consumption. Use the result for product selection and pricing; final production details should be confirmed with the order.