A Guide: How to Measure Windows for Curtains

measure window for curtain rodsWhen you order drapery rods online, it’s crucial to select the proper size for your particular window and drapery design. Unfortunately, there is no standard size when it comes to windows. Even in the same room, windows that look identical may vary slightly in size.

It’s important to consider just how you want the finished window treatment to look and function before you buy. Here are some things to watch when you measure for your curtain rods

What does it mean for curtains to “stack”?

The “stack” is the amount of space the curtains will take up when completely open, and bunched up at the sides of the windows. It’s important to add the depth of the stack to one (for a one-way draw) or both (when you want a center opening) ends of the rod when you measure. You don’t want to crowd the window, but you also don’t want the rod to extend beyond the stack on the sides—then it looks like a hat too big for its head!

For pinch-pleated draperies on traversing rods, we offer a guide below. Other styles of draperies will stack differently, and the weight of the fabric also affects the stack, so consult with your fabricator or play around with your draperies to find out what is most pleasing to you. You must calculate the stack even if your draperies will always be open (stationary panels).

How high should I hang my curtain rods? The height of the drapery can create an optical illusion and make your ceiling look higher. Generally, the higher the drapery is mounted, the better and more dramatic it will look.

It is best to mount the rods so that the top of the draperies is at least four inches above the top of the window or molding. However, you may not have that much space, or you may be installing curtains inside an alcove that does not allow a lot of room. That’s okay—work with what you have! The height of the installation does not affect the rod’s width.

How to Measure for Curtain Rods

First, measure the width of the window, side to side, including the molding/frame, if any. If you are using pinch-pleated draperies on a traversing rod, the chart below will give you a good idea of the extra width you will have to add to your rod. 

  Frame Width Rod Width
Up to 50” Frame width PLUS 10”
51” to 60” Frame width PLUS 12”
61” to 70” Frame width PLUS 14”
71” to 80” Frame Width PLUS 16”


Say you are starting with a window frame that is up to 50 inches wide. Add ten inches to that measurement, and an additional two inches for up to each additional ten inches of frame width. Look at the chart to find your window's range and add the specified number of inches to the width, and that will be the width of the rod you need.

The extra rod width will be evenly added to each side of the window for a center draw, and only added to one side for a one-way operation.

measure window for curtains

Note that in the second picture, the window appears to be larger and more open than the one above. This is because the stackback has been added to the window width.

Sheer Curtain Rod

Sheer curtains can be seen through, which sometimes creates an exception to the chart. If the sheers will be stationary, it will look odd if they extend far beyond the window’s frame, as you can see the wall through the sheer. In that case, add only three or four inches to each side of the window.

Curtain Rod for Valance over Draperies

If you opt for a valance over your drapery treatment, it should be long enough to cover the rod and pleats at the top of the drapery, but the valance rod should only be four inches or so wider than the under-treatment. Again, you don’t want it to look like something is missing at the sides of the draperies!

Drapery Hardware Solutions at Drapery Rods Direct

Drapery Rods Direct offers many different options for you to create beautiful, functional window treatments that will enhance your home’s décor for years. Nearly all the decorative collections can be customized to perfectly fit your windows, and there are many clever options to cover tricky windows. If you have questions about curtain rod length or you need special help with sizes, call our expert customer service associates at 800-251-5009 Monday through Friday, 9:00 am to 5:00 pm Eastern time.

Back to blog