Measuring Your Windows Correctly: The Essential Guide to Custom Window Treatments

Measuring Your Windows Correctly: The Essential Guide to Custom Window Treatments

Accurate measurements are the foundation of perfect-fitting custom window treatments. One small mistake during measurement can result in treatments that don't hang properly, don't cover the window, or look disproportionate in your space. Here's how to measure like a professional.

What You'll Need

Gather a metal measuring tape—not a fabric one, which can stretch—a notepad, and a helper if possible. Avoid measuring at the very edges of frames where dust collects or wood might be warped.

Measure Width First

For inside mount treatments, measure the width of the window opening in three places: top, middle, and bottom. Use the smallest measurement, as window frames may not be perfectly square. For outside mount treatments, measure the wall area where you want your treatments to extend, adding width on each side for proper coverage. Most professionals recommend extending treatments at least three to six inches beyond the window frame on each side.

Measure Height Carefully

Again, take measurements in three places: left side, center, and right side. For inside mounts, measure from the top of the frame to the sill. For outside mounts, measure from where you want the treatment to begin to where you want it to end. Decide if you want your treatment to touch the floor, hover slightly above it, or end at the sill.

Check for Level and Plumb

Windows aren't always perfectly level. Use a level tool to identify any sloping. Custom treatments can be designed to account for slight imperfections, but your installer needs to know about them in advance.

Note Obstacles and Details

Record the location of handles, radiators, air conditioning units, and any architectural features. If your window has a deep sill, crown molding, or unusual trim, these details affect how your treatments will hang and function.

Common Mistakes to Avoid

Don't measure over curtain rods that are already installed. Don't round your measurements up or down. Don't assume all windows are the same size. Don't measure at a time when your window is open or partially open.

Double-Check Your Work

Measure each window twice, and if you're ordering multiple treatments, verify which measurements correspond to which window. Many installation issues stem from measurement errors, which are entirely preventable with careful attention to detail.