How to Measure Windows for Curtains

Measuring for curtains is straightforward once you know what you are actually measuring. Most mistakes come from measuring the glass instead of planning the full coverage, or from skipping the fullness calculation. Here is the complete process.

What you need

A steel tape measure. Not a cloth tape, which stretches and gives inaccurate readings. A step ladder if your rod will be high. Something to write with. That is it.

Step 1: Decide where the rod will sit

Curtain length is measured from the rod down, so the rod position has to come first. Mounting the rod several inches above the window frame, or closer to the ceiling, makes the window look taller. Decide where you want it before you measure anything else.

Step 2: Measure the width

Measure the full width of the window frame. Then add a few inches on each side so the curtains extend past the frame. The total is your coverage width. Curtains that only span the glass look under-sized and leak light at the edges when closed.

Step 3: Calculate fullness

Fullness is how much wider the fabric is than the coverage width, and it is what makes curtains look luxurious rather than flat. Multiply your coverage width by 1.5 for a relaxed look or by 2 for a fuller, more formal drape. Divide that number by the number of panels to get the width of each panel.

Step 4: Measure the length

Measure from the rod down to your chosen ending point. The three standard options are just below the sill, just above the floor with about half an inch of clearance, or lightly touching the floor with an extra inch or two. Decide which look you want before you measure.

Step 5: Record in inches

Write everything down in whole or half inches. Never round to the nearest foot. A few inches of rounding error is clearly visible once the curtains are hung.

Common mistakes

Measuring the glass instead of planning the coverage width. Forgetting to account for the rod position when measuring length. Skipping fullness and ordering panels at exactly the coverage width. Rounding to the nearest foot.

The full walkthrough, including diagrams of each step, is in our step-by-step measuring guide. When your numbers are ready, the configurator turns them into a price for your exact size.