Inside Mount vs Outside Mount: Which Is Right for Your Windows?

Before you measure a single window, you need to make one decision: inside mount or outside mount. It's the choice that determines how your shade fits, how it looks, and how you measure — and getting it wrong means reordering. Here's everything you need to know to make the right call.

What's the Difference?

Inside mount — the shade installs inside the window frame. The headrail sits within the frame recess, the fabric hangs inside the window opening. The window trim remains visible on all sides. The shade looks built-in and architectural.

Outside mount — the shade installs outside and above the window frame, on the wall or ceiling. The shade covers the entire window opening and overlaps the frame on all sides. The window trim is hidden behind the shade when it's lowered.

Both work. Both look good. The choice depends on your window's specific characteristics and what you're trying to achieve.

When to Choose Inside Mount

Inside mount suits windows with a deep enough frame to accommodate the headrail — typically at least 2.5 inches of depth from the front edge of the frame to the glass. If your frame is shallower than this, inside mount isn't an option.

Beyond the depth requirement, inside mount is the better choice when:

You want to show the window trim — if your window has attractive trim or architectural detail, inside mount keeps it visible. The shade sits within the frame without covering the surrounding millwork.

You want a clean, minimal look — inside mount installations look flush and intentional. The shade appears to be part of the window rather than added on top of it.

Your windows are a standard shape — inside mount works best with rectangular windows that have consistent frame depth. Irregular or shallow frames complicate inside mount installation.

When to Choose Outside Mount

Outside mount is more forgiving than inside mount and suits a wider range of window conditions.

Shallow frames — if your frame depth is less than 2.5 inches, outside mount is the answer. The shade mounts to the wall above the frame rather than inside it.

Maximum light blocking — outside mount shades overlap the window frame on all sides, eliminating the edge gaps that occur with inside mount. For blackout roller shades in bedrooms or nurseries where complete darkness matters, outside mount provides noticeably better light blocking.

Making windows appear larger — mounting the shade high above the frame and wide beyond the frame edges makes windows appear taller and wider than they actually are. This is a standard interior design technique for small rooms or low-ceiling spaces.

Blinds for wide windows — very wide windows often have frames that aren't deep enough for inside mount across the full width. Outside mount works regardless of width.

Covering an unattractive frame — if the window frame is damaged, stained, or simply not worth showing, outside mount covers it completely.

How to Measure for Each

Inside Mount Measurement:

• Measure the inside width at three points — top, center, bottom — record the smallest value
• Measure the inside height at three points — left, center, right — record the smallest value
• Enter exact measurements to the nearest 1/8" — the factory adjusts for fit automatically
• Check window handle height — if the handle extends too far into the frame, it may interfere with the shade

Outside Mount Measurement:

• Decide how much overlap you want beyond the frame on each side — 3" per side is standard
• Measure total desired width: frame width plus overlap on both sides
• Measure total desired height: from mounting point to desired drop — mounting above the frame makes windows appear taller
• Extend 2–3" below the sill for complete coverage

The Rule of Thumb

If your frame is deep enough and you like the look of visible trim, inside mount. If you want maximum light blocking, larger-looking windows, or you have a shallow or awkward frame, outside mount.

When in doubt, outside mount is more forgiving — it's easier to achieve a good result and the light blocking performance is better.

Our team at BlindsMagic reviews measurements before production if you're not sure — send your measurements and we'll confirm before your custom roller shades, motorized zebra shades, or motorized cellular shades go into production.

Browse our full range at BlindsMagic.com.