Fit tools

Curtain Rod and Panel Size Calculator

Enter your window and ceiling height. We size the rod, count the panels and pick the ready-made length to buy, with the same rules as our curtain guide.

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Short answer

High, wide and full Hang the rod 4–6″ above the frame or halfway to the ceiling, and run it 3–6″ past each side (8–12″ if open curtains should clear the glass). Buy panels that add up to 2–2½× the rod’s length, in the ready-made length just above your rod height, and hem them to float ½″ above the floor.

4–6″

rod above the frame

2×

fabric width vs. rod

½″

hem above the floor

Curtains change how big a window, and a wall, looks. Hung high and wide, open panels sit beside the glass and the window reads taller; hung low and narrow, they cover glass and stop mid-wall. The calculator above turns the rules into a shopping list.

Worked example: a 36″ window in an 8′ room

  • Top of the frame at 84″, ceiling at 96″: halfway puts the rod at 90″.
  • 6″ past each side makes a 48″ rod.
  • At 2× fullness that’s 96″ of fabric: two 50″ panels.
  • From the rod to ½″ above the floor is 89½″, between the 84″ and 96″ ready-made lengths. Buy 96″ and hem 6½″, or take up the difference with clip rings.

Ready-made lengths and where to hang the rod

Panel lengthRod (or ring bottoms) for a ½″ floatFor a 2″ break
63″63½″61″
84″84½″82″
96″96½″94″
108″108½″106″
120″120½″118″
Heights from the floor. Ready-made lengths from Crate & Barrel and The Home Depot.

That’s why the calculator sometimes suggests moving the rod instead of hemming: if a 96″ panel is 2″ too long, raising the rod 2″ fixes it, as long as the wall above the window allows it.

The numbers we used

These are the same numbers as in our curtain guide. Where they come from is listed under Sources at the end.

4–6″

Rod above the frame

½

Of the way to the ceiling

3–6″

Rod past the frame

8–12″

To clear the glass

2–2½×

Fabric fullness

½″

Float above the floor

Measure this first

  • Window width at the outside edges of the trim.
  • Floor to the top of the trim, and floor to the ceiling.
  • Wall space beside the window: corners, closet doors, a headboard.
  • With rings or clips, the drop from the rod to the bottom of the ring.

Questions people ask

How wide should a curtain rod be?

The window width plus 3–6″ on each side, or 8–12″ each side if you want the open curtains to stack beside the glass. A 36″ window takes a 42–60″ rod.

How many curtain panels do I need?

Multiply the rod length by 2 (or 2½ for a fuller look) and divide by the panel width, then round up to an even number for a pair. A 48″ rod at 2× needs 96″ of fabric: two 50″ panels.

What length curtains for an 8-foot ceiling?

With the rod halfway between an 84″ frame and the 96″ ceiling, at 90″, you need 89½″ panels for a ½″ float. Buy 96″ and hem them, or use clip rings to take up the extra.

Should curtains touch the floor?

Hover about ½″ above it or just touch. Add about 2″ for a soft break, or 4″ or more to puddle; in a small bedroom, skip the puddle.

Read the full curtain guide

Seven curtain tricks that make a small bedroom look bigger, with a worked example.

How high to hang curtains

Related: How to cool a small room without AC · Small living room with a bay window

Sources