Measure track/pole width × fullness ratio (e.g. 2.5×) to get the total fabric width needed. Divide by your fabric width to get the number of panels (widths). Multiply by the drop length + hem + heading allowances.
Fullness ratio is how much wider the fabric is than the track, creating gathers. Pencil pleat needs 2–2.5×, pinch pleat 2–2.5×, eyelet 1.5–2×, tab top 1.5×, and sheers 2.5–3×. Flat/Roman blinds use 1–1.2×.
Measure from the pole or track top to where you want the curtain to end: sill length (1cm above sill), below sill (+15–25cm), floor length (1cm above floor), or puddle (+15–25cm below floor). Our calculator uses the finished drop you enter.
Each fabric width must start at the same point in the pattern to match across panels. Enter the vertical pattern repeat distance — the calculator adds one extra repeat per fabric width to allow for matching.
Always add at least 0.5m per window as a safety buffer. Pattern-matched fabrics, beginners, or complex styles should add 10–15% more. Buy from the same roll/dye lot to ensure consistent colour.