How to Measure Room
Windows

How to Measure Curtain Rod Length

Measure the window frame's outer width, then add 4-6 inches on each side for the standard look — an 8-12 inch total addition — to get the rod length to buy or cut to.

Measure the window frame’s outer width, then add 4-6 inches to each side for the standard look — that’s 8-12 inches on top of the frame width, total. A 36” window frame calls for roughly a 44-48” rod.

The basic formula

Window frame width + (overhang per side x 2) = rod length

The overhang is a style choice, not a fixed number, but there’s a reliable range:

Look Overhang per side Total addition
Standard 4-6 in 8-12 in
Wider / more dramatic 8-12 in 16-24 in

The point of the overhang is functional as well as visual: it lets the curtain panels stack fully outside the glass when open, instead of covering part of the window and blocking light.

Measuring an already-installed window frame

  1. Measure the frame’s outer width at the top, middle, and bottom — use the widest of the three if they differ.
  2. Choose your overhang (4-6” per side is the safe default).
  3. Add the overhang to both sides of the frame width to get your target rod length.

Example: 32” frame width, 5” overhang per side → 32 + 5 + 5 = 42” rod length.

If you’d rather skip the arithmetic, this is exactly the calculation our curtain rod calculator handles — enter the window width and it returns the recommended rod length.

Bracket-to-bracket vs. overall rod length

Adjustable curtain rods are sold with a bracket-span range (for example, “48-84 inches”), which is the distance between the two wall brackets — this is the number that needs to match your target rod length. The rod’s fully-extended overall length, including finials, is usually a couple inches longer on each end and isn’t the number to match against your measurement.

Checking clearance before you commit

  • Confirm there’s enough wall space on either side of the frame for your chosen overhang — a rod can’t extend past a perpendicular wall or into a corner.
  • Check bracket projection (how far the bracket holds the rod off the wall) against any window trim or blinds hardware already in place, so the curtains clear them when closed.
  • For multiple windows on one rod, measure outer-edge to outer-edge across all the windows, then apply your overhang to the two outermost ends only.

Curtain Rod Length Calculator

Window width in, rod length and fabric yardage out.

Overhang style

Recommended rod length

—

Frequently Asked Questions

What's the standard formula for curtain rod length?

Window frame width + (4 to 6 inches x 2 sides). For a 36" window, that's 36" + 8 to 12" = a 44-48" rod. This is the most common starting point; adjust the per-side overhang up or down based on how wide you want the finished look.

How much longer should a curtain rod be than the window?

8 to 12 inches longer than the window frame's width in total (4-6 inches on each side) is standard. Going wider — up to 10-12 inches per side — makes the window look larger and lets more light in when curtains are open, but requires enough clear wall space on either side of the frame.

Do you measure a curtain rod from bracket to bracket or end to end?

Bracket-to-bracket is the number that matters for fit and for matching a rod's stated size range (most adjustable rods are sold with a min-max bracket-to-bracket range, like "48-84 inches"). The rod's total end-to-end length is usually a bit longer to allow for finials and adjustment overlap, so always check a product's bracket-span spec, not just its overall length.

Can you use one curtain rod for two windows next to each other?

Yes, if there's a reasonable amount of wall space between them — measure from the outer edge of one window to the outer edge of the other, then add your standard overhang (4-6 inches) to each end, the same way you would for a single window.

← Back to Windows