How To Measure For Outside Mount Blinds

How to Measure for Outside Mount Blinds

While inside mounting blinds is the more traditional approach, outside mounting blinds offer certain advantages many homeowners find appealing. In this ultimate guide, we discuss the pros and cons of outside mounting your blinds, provide a measuring guide for outside mount blinds, and provide a step-by-step process on how to install outside mount blinds for the perfect fit.

Next, we’ll walk you through outside mounting both vertical and horizontal blinds, and, finally, we’ll discuss whether or not you need to use extension brackets or spacer blocks when outside mounting your blinds.

How to Install Blinds Outside Window Frame

Outside mounting blinds satisfy the basic need for a window covering, while providing proper light control for your new window. When it comes to installing them, basic tools are all that you need, really, since most of the materials for installation already come along with the outside mounting blinds you are getting.

Let’s go over the steps to install blinds outside window frame:

  • Unpack your blinds and lay out all the materials you need before proceeding with the installation. Much like any DIY project, you must be sure that everything you need is ready for smooth sailing all throughout.
  • Hold up the blinds to your window opening and get the right sides for installing them, then get the accurate measurements and mark the outside corners with a pencil. When fully extended, they may not cover the bottom of the window if installed too high or too low.
  • Use the materials provided to drill or screw the brackets into the wall or window trim. Install the center bracket, if provided, slightly out of center to avoid obstructing the center cord of the blinds. Using a steel tape measure, mark your center bracket location and drill or screw.
  • Get your valance clips and place them in the front of the blinds before mounting them. The valance clips attach the valance to your blind, so make sure they do not interfere with the components above.
  • Attach the headrail to the brackets, close the end brackets, and make sure they are securely fastened.
  • Install your valance by attaching the side pieces to the main piece, then insert the headrail into the brackets and close the brackets securely.

Make sure your new blinds work by opening and closing them, and that’s basically it. Consider getting these stylish faux wood blinds to further enhance the look of your space!

How to Install Outside Mounting Horizontal Blinds

When learning how to install outside mount blinds, you will need a pencil, a measuring tape, and either a drill or a screwdriver, a hammer, and a nail. You might also want a leveler to ensure the blinds are absolutely straight.

Outside mounting horizontal blinds are a bit different from outside mounting vertical blinds, so we’ll walk you through horizontal blinds first, and then move on to vertical blinds.

  1. First, remove the blinds and all hardware from the package and lay everything out to ensure you have all the parts. Review the instructions that came with the blinds for any specific guidance.
  2. Find the center of the window and make a light mark with the pencil. Grab the headrail and decide how high you want to install it, then center it on the pencil mark you just made and use the leveler to ensure it’s straight. Mark the edges of the brackets or the screw holes if you can angle your pencil to do so.
  3. Create a pilot hole for the screws, either by using a drill bit or by tapping a nail partway into the wall with the hammer, and then removing the nail. Screw the brackets into the wall and double check they are securely fastened.
  4. Place the headrail into the brackets. Either snap the headrail into place or close the clips that secure it, depending on the style of blinds you purchased.
  5. Next, secure the clips on the headrail and attach the valance to it. The valance is the trim that covers up the hardware at the top in order to make it more aesthetically appealing.

And, you’re done! Test the window blinds by raising and lowering them as well as opening the slats if applicable, and enjoy your new outside mount horizontal blinds.

mounting vertical blinds

How To Install Outside Mounting Vertical Blinds

Outside mounting custom vertical blinds require slightly different steps because you will have to attach the vanes (the wide vertical slats) after mounting the headrail. Here are the steps to outside mount vertical blinds:

  1. First, remove the blinds and all hardware from the package and lay everything out to ensure you have all the parts. Review the instructions that came with the blinds for any specific guidance.
  2. Decide how high you will install the vertical blinds. They need to be high enough that the vanes will not touch the ground or drag along it. Most people install their vertical blinds so the vanes hang 2-3 inches above the ground. Lightly mark this height with your pencil.
  3. Find the center of the window and make another light mark with the pencil. Center the headrail on the pencil mark you just made and raise it to the height you determined in the previous step. Use the leveler to ensure the headrail is straight, and mark the edges of the brackets or the screw holes if you can angle your pencil to do so.
  4. Create a pilot hole for the screws, either by using a drill bit or by tapping a nail partway into the wall with the hammer, and then removing the nail. Screw the brackets into the wall and double check they are securely fastened. Place the headrail into the brackets and secure it.
  5. Small plastic clips should hang from the headrail; these clips are designed to hold the vanes. Carefully pry each clip apart and insert a vane into it, making sure the clip closes securely. Repeat this until all the vanes are filled.
  6. If your vertical blinds came with a valance, attach the clips for that to the valance and attach the valance to the clips.
  7. Test the vertical blinds by opening and closing them, as well as moving them back and forth. Enjoy your new outside mount vertical blinds!

Comfortable workplace near window with horizontal blinds

How To Measure For Outside Mount Blind

Whether you’re committed to outside mount blinds or just trying to confirm you have enough room to mount, it’s important to properly measure for outside mount blinds. To do this, you will need a tape measure and a pencil, as well as some way to make a note of your measurements—a note on your phone works, as do paper and pen.

Get Custom Vertical Blinds to Fit Your Exact Needs
  • First of all, measure from the top of the window to the bottom of the ceiling or crown molding, or whatever is above the window. You will need a minimum of 2 inches of vertical space in order to outside mount your blinds. If you don’t have that space, you will have to inside mount them.
  • Measure the width you want covered at three points: the top, middle, and bottom of the window, and use the largest one as your measurement. For horizontal blinds, we recommend a minimum of ¾ inch overlap on each side, for a total of 1.5 inches of overlap. For vertical blinds, you will want even more overlap: 1.5 inches on either side, for a total of 3 inches. In either case, you may choose to have your blinds extend past the window even farther if you would like more light blockage.
  • Determine how far above the window you will mount the headrail. You may choose to install it into the window trim, if it is wide and flat enough, or you may wish to drill it directly into the wall. Mark this location on the wall with a faint pencil line.
  • Measure from the mark you just made to where you would like the blinds to fall below the window. If you have a protruding window sill , use that as your bottom placement. If your window sill doesn’t protrude, you can decide where you would like the blinds to rest below the window. Also mark this lightly with your pencil. Using the marks you just made, measure the total vertical length you would like the blinds to have.
  • See if there are any obstructions that could stop the blind from being raised or lowered. If there are, determine whether you will need any spacer blocks or extension brackets in order to outside mount the blinds in your chosen location.
  • Don’t take any deductions from your measurements, and double check all your measurements are correct and expressed as W x H. Be forewarned, the factory will not take deductions—the measurements you enter are the measurements you get—so make sure they are correct before submitting your order.

Measuring for Outside Mount blinds

 To learn more about measuring for blinds of all types, check out our guide that explains how to measure windows for blinds .

When Should You Outside Mount Your Blinds?

After learning how to install window blinds outside mount, you might be eager to install them right away. Before you decide, let's look at the reasons when you should outside mount them, rather than use inside mount blinds.

When Should You Outside Mount Your Blinds

  • Often, older homes have windows that are not in the regular square shape, leaving inside mount blinds out of the equation.
  • You prefer completely uncovered windows when the blinds are raised.
  • To give the illusion of taller windows, by installing the blinds closer to the ceiling.
  • The window frame is not in a not-so-great condition, which could benefit from being covered instead.
  • The windows do not provide enough depth to support inside mount blinds.
  • Some inside mount blinds cannot provide enough protection against light leaking from the window.
  • You intend to install two window treatments, one with the inside mount and the other with the outside mount.
Learn How to Measure Windows for Blinds

Benefits Of Outside Mount

Window treatments are an important part of any room, as they provide privacy, insulation, and protection from the sun’s rays. Outside mount blinds are one popular type of window treatment that offers a variety of benefits:

  • Outside mount blinds provide protection from light gaps that inside mounts cannot.
  • Inside mount shades are difficult to install on some windows, particularly those with shallow window casings.
  • As most doors don't provide enough depth for window frames, it is difficult to install inside mounts on them.
  • You can hide with outside mounts your window's imperfections, such as scrapes and blemishes, while giving the illusion of a taller window as these are completely covered.

Things to Look Out for When Installing Outside Mount Blinds

You need to be aware of some things even after learning how to install blinds outside mount. When certain rules are not followed, these shades can lose their aesthetic value and overall purpose.

  • From the narrowest to the longest measurement, accuracy is important when installing outside mount blinds. Start by measuring the width and then the height, then round off to the nearest 1/8th inch. Also, remember that the measuring instructions for vertical and horizontal outside mount shades differ.
  • Be sure to allow extra space for your headrail and any materials such as mounting brackets you will need to install, to maximize your blind's ability to block light leaks and to provide optimal privacy.
  • You will also need to provide additional considerations for possible obstructers, such as deadbolts or molding, that may get in the way of installing your outside mount.

When Should You NOT Outside Mount Your Blinds?

Despite their many advantages, outside mounting blinds aren’t appropriate for all circumstances. Here are some situations when you might want to inside mount your blinds instead:

  • You don’t have enough space above the window to install the blind hardware directly into the wall or window trim.
  • You plan to hang curtains above the window, which will be difficult, if not impossible, with outside mounted blinds.
  • You plan to put furniture or other objects relatively close to the window, which might bump into outside mounted blinds.
  • Your windows are surrounded by high-quality window trim you want to be visible even when the blinds are closed.
  • You have a deep window recess you want to take advantage of.
  • You want the blinds to sit flush with the wall and not stick out.
  • All the other blinds in your home are inside mounted and you want a consistent look.

When Should You Not Outside Mount Your Blinds

Do My Outside Mount Blinds Need Extension Brackets?

As the name suggests, extension brackets extend farther than a standard bracket, holding outside mount blinds even farther away from the window. You might want to use an extension bracket for several reasons; for instance, to keep the shades from hitting protruding window trim or a secondary inside mount window treatment.

Extension brackets are best used when you need the blinds to stick out several inches, whereas spacer blocks are a better choice when you only need to push the blinds out a little bit—more on spacer blocks in the next section.

There are two main designs available for extension brackets. In the more common design, the longer arm is integrated into the bracket itself, forming a capital L shape with one short arm and one long arm. In the less common design, the extension bracket is a free-floating flat metal piece that is attached to one arm of the standard bracket using a screw.

You can install extension brackets using the same steps outlined above. You’ll measure and mark the placement, and then screw the extension bracket into the wall. Next you will attach the bracket that holds the headrail of the blinds to the extension bracket and secure the headrail to the regular brackets.

Do My Outside Mount Blinds Need Spacer Blocks?

If you only need your blinds to stick out between ½ and 1 inch, you will probably want to use spacer blocks instead of extension brackets. Spacer blocks look like a small grid made of plastic or rubber, and they go between the bracket and the wall. Spacer blocks are helpful to use if you are screwing the bracket into a wall or window trim that is uneven or slanted.

To use spacer blocks, go ahead and mark the placement of the screw holes and drill the pilot holes. Then place the spacer block over the pilot holes, making sure the holes in the spacer block align with the pilot holes.

Next, put the bracket on top of the spacer block and line up the holes once again. Drill through the bracket and spacer block and into the wall using long drywall screws.

Refer to Our Guide

Outside mounting your blinds offers many advantages and can be an excellent choice in many instances. If you’re planning to outside mount blinds in your home, refer back to this guide as needed to make sure you are measuring and installing them correctly. If you’re looking to buy blinds in bulk, check out our commercial window shades.


What is the measurement for an outside mount for a window that is 56" wide?

Outside mount blinds should extend around 3 inches over each side of the width of the window, so a 56" wide window will appropriately require a 62" wide blind. The overlap may be less and wider depending on the type of window, but this is a general rule that you can rely on.

How do you measure for outside mount blinds?

You can measure for outside mount blinds with just a steel tape measure, pencil, as well as a notepad. Measure the width 3 inches beyond each side of the window and the length to a point just below the bottom of the window sill. The width should always be noted first, followed by the height.

What is the size of the window?

The size of the window when installing outside mount blinds includes the mounting bracket above the window opening for the height, and the bottom includes the sill and apron below the window. Round off your measurements to the nearest 1/8 inch.

What is the difference between inside mount and outside mount blinds?

Simply put, inside mount blinds fit inside window frames, while outside mount blinds fit outside the frames. Your window coverings will function differently depending on which mounting style you choose.


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