Inside Mount vs Outside Mount Blinds for Shallow Window Frames | Which Fits

Outside mount blinds are usually the right choice for a shallow window frame, because they attach to the trim or wall above the opening and never depend on the frame’s mounting depth.

This call decides whether the blind covers the glass or blocks your favorite chair, so make it before you order—your measurements change with the answer. Below are the spec numbers to test against and the measuring sequence for each route.

Inside Or Outside Mount For A Shallow Frame?

Inside mount works only when the frame has enough usable depth for brackets, headrail, and valance. Outside mount screws into the trim, sheetrock, or wall beside the opening, so depth stops being a factor, and it covers more of the window by overlapping the opening rather than sitting inside it.

For shallow openings, outside mount is often the better answer even when inside mount is technically possible. It can mask a narrow or out-of-square opening and wins on light blocking and privacy because its edges extend past the glass. It does hide more of your trim, which is the one thing inside mount protects.

How Deep Does A Window Frame Need To Be?

No single number exists — it depends entirely on the blind you buy. A frame is too shallow whenever its usable depth is less than the minimum the product specifies.

Blinds.com’s published specs show the spread: a 2 Inch Faux Wood Blind needs just 3/4 inch of inside-mount depth, while the Premium Cordless 2 Inch Faux Wood needs 1 5/8 inches and up to 4 1/16 inches for a full recess with the Crown Valance.

Measure the depth exactly where the brackets will sit — not at the front lip of the casing, the mistake that sends people back to the store. If your frame falls short on the spec sheet from Blinds.com’s roller and solar shade measuring instructions, treat it as too shallow and move to outside mount.

How Do You Measure For Each Mounting Type?

Inside mount measures the opening; outside mount measures the space you want covered. Mixing them up is the most common ordering error.

Inside mount:

1. Measure width at the top, middle, and bottom of the opening.
2. Record the narrowest width.
3. Measure height at the left, center, and right.
4. Record the shortest height.
5. Write everything to the nearest 1/8 inch with a steel tape.

Outside mount:

1. Confirm a flat surface above the opening — at least 2 inches is the usual recommendation for brackets.
2. Measure the area you want covered, width first, height second.
3. Add 2 1/2 inches at the top for bracket space on roller and solar shades.
4. Add roughly 3 inches per side for privacy and light control, unless the product says otherwise.

Outside-mount blinds are built to your exact dimensions, so no factory deduction rescues a wrong number. If you want a head start on products built for tight frames, our tested blinds for shallow windows roundup pairs well with these measurements.

What Are The Most Common Measuring Mistakes?

Most failed installs trace back to six avoidable errors:

• Measuring the casing’s front depth rather than the bracket depth.
• Picking inside mount without checking the product’s minimum depth spec.
• Measuring once instead of three width and three height points.
• Ordering an outside-mount blind using inside-opening dimensions.
• Forgetting bracket clearance above the frame.
• Ignoring window handles or cranks that block the blind’s travel.

When both routes fit, inside mount keeps the window tidy; when the frame is genuinely shallow, outside mount is the route that installs. Lean on the spec sheet, not the product’s name.