Tools / Calculator

Curtain Size Calculator

Enter your window measurements and get the curtain rod width, the number of panels and the curtain length to buy.

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Units
Curtain length
Fullness
Result

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How to measure

  • Window width: outside edge to outside edge of the frame, including the trim.
  • Floor to the top of the frame: from the floor to the top edge of the trim.
  • Window height, for sill-length curtains only: top of the frame to the sill.

The rules the calculator uses

  • The rod is wider than the window. It passes the frame by 8 inches on each side, so open curtains stack over the wall and not over the glass. The window looks wider and lets in more light.
  • The fabric is wider than the rod. Flat curtains look like bed sheets. Twice the rod width is the standard fullness, one and a half times looks tailored and suits heavy fabric, and two and a half times suits sheers.
  • Panels are counted in pairs. Most ready-made panels are 50 to 52 inches wide. The calculator adds a second pair only when one pair would fall well short of the fullness you chose, and shows the fullness you actually get.
  • Floor-length curtains stop half an inch above the floor. The calculator picks the standard length that reaches the floor and tells you how high above the frame to hang the rod to make it land there.
  • Sill-length curtains end 4 inches below the sill.

Standard lengths

63, 84, 96, 108 and 120 inches. 84 suits a standard 8-foot ceiling with the rod just above the frame. 96 lets you hang the rod close to the ceiling, which makes a low room look taller.

In a small room

Hang the rod high and wide, and choose curtains close to the wall color. The window reads as larger and the wall as taller. Short curtains that stop at the sill cut the wall in two; keep them for kitchens, bathrooms and windows above furniture or radiators.

Before you buy

Check what the length includes. Grommet and back-tab panels are measured from the top edge, but they hang about an inch below the top of the rod. Panels on rings hang an inch or two lower still.

More ways to make a small room look bigger are in small living room furniture ideas.

Use this calculator on your site

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