Inside vs outside mount blinds

Inside mounts sit neatly in the frame. Outside mounts cover more and hide problems. Here's how to choose.

Friends share dinner around a wooden table in front of windows dressed with linen roman shades

Short answer: inside mount is the most popular choice.^{[1 · Oct 29, 2026]} Pick outside mount when the frame isn't deep enough, the window is out of square, handles or cranks are in the way, or you want less light around the edges.^{[1 · Oct 29, 2026]}^{[2 · Oct 29, 2026]}^{[3 · Oct 29, 2026]}^{[4 · Oct 29, 2026]}

Side by side

	Inside mount	Outside mount
Where it goes	Inside the window frame^{[1 · Oct 29, 2026]}	On the wall or trim around the window^{[1 · Oct 29, 2026]}
Look	Sits within the frame, so the trim stays on show (our observation)	Can make a window look larger and hide plain or worn trim^{[1 · Oct 29, 2026]}^{[2 · Oct 29, 2026]}
Light gaps	Small gaps at each side^{[2 · Oct 29, 2026]}	Fewer gaps; better light control and privacy^{[1 · Oct 29, 2026]}^{[3 · Oct 29, 2026]}
Depth needed	A minimum recess for each product^{[1 · Oct 29, 2026]}	None, but you need flat wall above for brackets^{[5 · Oct 29, 2026]}^{[2 · Oct 29, 2026]}
Out-of-square frame	May not work or look its best^{[4 · Oct 29, 2026]}	Recommended^{[4 · Oct 29, 2026]}^{[2 · Oct 29, 2026]}
Handles and cranks	Can get in the way^{[2 · Oct 29, 2026]}	Clears them, with extension brackets if needed^{[2 · Oct 29, 2026]}^{[1 · Oct 29, 2026]}
The view when raised	The stack can block part of the glass^{[2 · Oct 29, 2026]}	The stack can sit above the glass (our observation of the geometry)
Deductions	Factory trims the width slightly^{[1 · Oct 29, 2026]}^{[6 · Oct 29, 2026]}	None; made to exact size^{[2 · Oct 29, 2026]}^{[6 · Oct 29, 2026]}

Is my window deep enough for an inside mount?

Measure from the front of the frame back to the glass or the first thing in the way.^{[3 · Oct 29, 2026]} Each product has two numbers: the minimum depth to mount at all, and the depth to sit fully inside the frame.^{[1 · Oct 29, 2026]} In between, it mounts inside but sticks out. Blinds.com's example: a shade that needs 1 in minimum and 3 in to be flush, in a 1 in recess, sticks out 2 in.^{[6 · Oct 29, 2026]} If you don't have the minimum, an outside mount is required.^{[3 · Oct 29, 2026]}

Product (Levolor)	Minimum depth	Fully recessed
Cellular shades	½ in	2⅛ in
Roman shades	½ in	2⅛ in
Faux and real wood, 2 in slats	¾ in	2½ in
Roller and solar shades	1½ in	2½ in
Vertical blinds	2½ in	3 in headrail, 3¾ in vanes

Figures from Levolor's measuring guide and vertical blind technical guide.^{[1 · Oct 29, 2026]}^{[7 · Oct 29, 2026]} Other brands differ; the blind types guide has more.

How measuring differs

Inside: narrowest of three widths, longest of three heights, no deductions.^{[1 · Oct 29, 2026]}^{[3 · Oct 29, 2026]}
Outside: the area to cover plus overlap on each side, and height from the headrail position to the sill or wherever you want it to stop.^{[1 · Oct 29, 2026]}^{[3 · Oct 29, 2026]} Overlaps vary by brand, from ¾ in to 2½ in per side or more.^{[1 · Oct 29, 2026]}^{[3 · Oct 29, 2026]}

See how to measure for the step-by-step.

Sources: 1. Levolor, How to measure windows for blinds and shades. 2. Bali, Cellular and pleated shades measuring guide (PDF). 3. Blinds.com, How to measure. 4. The Home Depot, Measuring the right way for window treatments (PDF). 5. The Home Depot, Blinds category and buying notes. 6. Blinds.com, How to measure for a bay window. 7. Levolor, Vertical blinds technical guide (PDF). Checked Oct 29, 2026. Trademarks belong to their owners; figures are restated in our own words and tables, not reproduced.