Measure garments on their hangers
Hang a typical shirt, jacket and pair of trousers as you normally store them. Measure from the hanging point to the lowest edge, including the hanger. A folded trouser arrangement needs a different drop from trousers clipped at the waistband. Leave room so the garment does not rest on the rail or clothing below it.
Long dresses and coats need their own clear height. If there are only a few, one narrow full-height section may be enough. If they form most of the collection, double hanging will not provide the apparent gain in capacity promised by an empty wardrobe drawing.
Reach matters as much as capacity
An upper rail should be usable by the person it serves. Test the height with a real hanger and garment rather than reaching towards an empty mark on the wall. Lifting a coat onto a rail is different from touching that height with a hand.
Special pull-down fittings have their own dimensions, load limits and operating requirements. Check the exact product and whether the surrounding wardrobe allows its movement. Do not assume a mechanism makes every high compartment accessible to every user.
Consider the lower rail's relationship with drawers or shelves. Clothes should not lie over a drawer front or prevent it opening. The rail and its contents need a clear volume, not just a line on the plan. Check the internal depth so hangers do not press against the doors.
Divide by clothing, not symmetry
Two people sharing a wardrobe may need different rail heights and different amounts of long hanging. Matching interiors can waste space for both. Assign the bays according to the clothes and reach of each person, then use adjustable shelves for the remaining items.
Leave enough lateral space to slide hangers and remove a garment without pulling several out together. A rail packed solid may hold more pieces but make them harder to browse and return. If you are changing an existing wardrobe, try rearranging the clothes first. That experiment can reveal whether another rail is useful before buying the fitting.
