Windows & interiors
Turn three room measurements into a complete curtain plan: rod height, finished length, rod extension, and combined panel width.
8 in
above window trim
88 in
finished curtain length
Ends at the measured floor line.
Combined panel width (2–2.5× fullness)
128 in–160 in
Finished length is measured from the rod line to the floor. Check whether your rings, clips, grommets, or header place the fabric above or below that line before ordering.
Measure vertically from the finished floor to the ceiling beside the window.
From the same floor point, measure to the outside top edge of the window casing.
Measure the full outside-to-outside trim width, not just the glass.
Rod height = window-top height + chosen offset
The available wall gap limits the offset. The balanced mode uses roughly half the gap within a practical 4–8-inch range; high and near-ceiling modes use more of it.
The result is a target finished drop from the rod line. Rings, clips, grommets, tabs, and curtain headers change where the fabric starts, so compare that drop with the manufacturer's measuring diagram.
A common starting range is 4–8 inches above the top trim. When space allows, mounting higher can make the wall feel taller. Leave clearance below the ceiling and use the calculator for your actual gap.
Plan roughly 6–10 inches beyond the outside trim on each side. Wider extension lets more glass show when curtains are open, but the rod and brackets must still be properly supported.
Floor-length curtains can kiss the floor, touch it, break slightly, or puddle. A 1/2-inch clearance is practical for frequent opening, while a 1–2-inch break is softer and a 6-inch puddle is decorative.
The combined finished panel width is commonly 2–2.5 times the rod width. Two-times fullness gives a clean gathered look; 2.5 times gives a richer appearance, especially with lighter fabrics.
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