Step 1
Start with the hardware
Choose a wall or ceiling mount before setting the length. Use a steel tape measure, a pencil and a stable way to reach the measuring points. Measure each window independently, even when they look identical.
Record inches to the nearest ⅛ inch. Check handles, doors, radiators, furniture and the space needed for the curtain folds. Confirm a suitable mounting surface with your installer before ordering.
Step 2
Measure the full track width
Measure from one end of the planned track to the other, including any extension beyond the window. If space allows, 8–12 inches beyond each side is a useful starting point for parking the open curtains; thicker fabrics may need more room.
Write down the full coverage width once. Do not double it for fullness or halve it because you want a pair. The flat fabric width and finished coverage are not the same measurement.
The proposed hardware assortment covers straight 24–84 inch runs in whole-inch increments. Do not round a tight fit up or join tracks to work around the range. An opening outside that scope needs a different hardware solution.
Step 3
Measure the finished drop
Establish the actual curtain hanging point for your selected track, carrier and hook. It is not automatically the ceiling or the top of the rail. The final hook offset must be confirmed before an order can be cut.
Measure to the floor at the left, center and right. Record all three readings and any unevenness. For a clear-of-floor hem, use the shortest clearance as your starting point, then apply the chosen hem clearance only after the hanging-point offset is known.
Record a floor-skimming, break or puddle preference separately. Do not quietly add extra length to an exact measurement. A puddle uses more fabric and is less practical at a frequently used door.
Step 4
Choose where the curtains open
A single panel gathers to one side. A pair separates at the center and stacks to both sides. Make sure the chosen side has enough room and that the baton remains easy to reach.
Save the track width, all drop readings, mounting choice and single/pair preference. A saved project is not a manufacturing specification or an order.