How to use it
- Measure the width of the rod or track, then the drop from the rod (or curtain rings) to where the curtain should end.
- Set the gap above the floor or sill. A small gap such as 1 to 2 cm keeps the hem from dragging.
- Choose the fullness, one panel or a pair, and enter the hem allowances and the width of your fabric roll.
- Read the cut length of each fabric width and the total fabric length to buy.
How the numbers are worked out
- Finished length = drop - gap above floor.
- Cut length = finished length + hem and header allowance.
- Flat fabric width per panel = rod width x fullness / panels + side hems.
- Fabric widths per panel = flat width / roll width, rounded up to a whole width.
- Total fabric = widths per panel x panels x cut length.
Everything is plain arithmetic, so it works in any single length unit. Joining extra widths also uses up seam allowance, which the side-hem field can cover.
Worked example
A 200 cm rod, a 240 cm drop, a 1.5 cm gap, a pair of curtains at 2x fullness, 20 cm bottom allowance, 10 cm side hems and 140 cm wide fabric. Finished length 238.5 cm, cut length 258.5 cm. Each panel is 200 x 2 / 2 + 10 = 210 cm flat, which needs 2 widths of 140 cm. In total 4 widths x 258.5 cm = 1034 cm, or 10.34 m of fabric.
Tips
- Measure the window in several places and use the largest drop.
- Hang the rod wider than the window so the curtains clear the glass when open; use the real rod width here.
- Washable fabric can shrink; buy extra length if the label warns about it.