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How to Measure for Vertical Blinds

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Things to Consider
A man using a steel tape measure to measure the width of a window frame.

When measuring for vertical blinds, it’s important to remember a few key things:


  • A steel tape measure is much more accurate than cloth measuring tape.   
  • Always measure to the nearest 1/8 inch. Don't round to a half or whole inch.   
  • Be careful when writing down measurements. Always have width and height clearly marked. Remember, put your width measurement first and height last (W x H).   
  • Blinds can either be mounted inside or outside the window frame. This guide will help you decide which mount style you want and teach you how to measure for vertical blinds in either style. 
  • When measuring for inside mount blinds, always record the actual window opening size when you order. The factory will make the necessary adjustments for your product to fit into the window frame.   
  • When measuring for outside mount blinds, add at least 4 inches to every side of the window to make sure your room is private and that the blinds block enough light. 
  • The most common standard vertical blind sizes that you can buy quick ship or off-the-shelf range from 24-inch x 72-inch to 72-inch x 72-inch. Wider or longer vertical blinds typically require a custom order.  
  • Trimmable length vertical blinds allow you to cut the vanes to a shorter length at home. This is an easy way to get a custom height without ordering custom blinds. 
Choose Inside or Outside Mount Vertical Blinds
A window with inside mount vertical blinds on the left and a window with outside mount vertical blinds on the right.

It's important to decide whether you want your vertical blinds mounted inside the window frame or outside of the window frame (above and around the window) before you do any measuring.


  • Inside mount refers to a blind that is mounted to the inside of your window frame. This type of mount is by far the most common choice. It makes for a clean, custom appearance. Note that inside mount blinds require a minimum window frame depth to install correctly.  
  • An outside mount blind is typically used for windows in two situations: If there are obstructions inside your window frame, such as an alarm sensor, or if your window frame doesn’t have enough mounting depth to hold your blind.  
  • If you’re installing vertical blinds for a glass door, you’ll measure for outside mount blinds. 
  • Outside mounts have many benefits, such as hiding an unattractive window, or making a window seem even larger than it actually is. When figuring out where to place outside mount window blinds, account for the height of the blind’s head rail when you make your measurements. Take time to double check your measurements, as these blinds will be made for your exact window. 
Measuring for Inside Mount Vertical Blinds
A diagram of a window that shows where to measure the height and width for inside mount vertical blinds.
  • Measure the inside width of your window at the top where your blind will be mounted. This is the width measurement for your blinds.  
  • Measure the width of your window at the middle and at the bottom as well, to ensure its width is even throughout. If the measurements at these points differ too greatly, you may need to install outside mount blinds instead. 
  • Measure the exact height of your window in three places: left, middle and right. Choose the shortest of the three measurements. This is the height measurement of your blinds. 
  • Now that you have completed these few simple steps, you are ready to place your order. 
Measuring for Outside Mount Vertical Blinds
A diagram of a window that shows where to measure the height and width for outside mount vertical blinds.

The product details page for your blinds provides information on how much flat space is required around your window or door for installation. When you specify an outside mount, we will not take any size deductions. Your blinds will be made at the exact size you specify.


  • Determine the width of the blind you will order. If you have trim around your window or door, simply measure to the far edges of your trim from left to right. If your window or door has no trim around it, measure a distance from point A to point B that includes any extra width you’ll want for light gap coverage and privacy. We recommend adding 2 to 3 inches to each side.   
  • Determine the height of the blind you will order. If your window has a protruding sill, start from the sill and measure 2 inches beyond the top of your window opening to accommodate for mounting hardware. If your windowsill does not protrude, we suggest you begin your measurement 2 to 3 inches below the sill for maximum coverage. Then measure 2 inches beyond the top of your window opening or door frame to accommodate your hardware.   
  • Record your measurement to the nearest 1/8-inch increment. This is the height you will order. 

Now that you know how to measure for vertical blinds, you’re ready to find vertical blinds you’ll love. Remember to take careful and accurate measurements of each window or door to find the best fitting blinds for your home.  

Ready to find the right size vertical blinds for your windows and doors? Use The Home Depot Mobile App to locate products and check inventory. Snap a photo of a window treatment you like and use image search in The Home Depot Mobile App. We’ll show you similar products.