Inside vs outside mount blinds

An inside mount fits the blind within the window frame for a clean, built-in look. An outside mount fixes the blind to the wall or trim above the window so it overlaps the opening, which blocks more light at the edges and can make a window look larger. The right choice depends on your window depth, the trim and how dark or private the room needs to be.

Key takeaways: inside mounts look tidier but leave a small light gap at each side. Outside mounts overlap the opening and suit bedrooms and shallow frames. Window depth, handles and cranks decide what is possible. Custom blinds should be measured at the actual window, with the mount decided first.

What is an inside mount?

With an inside mount, the brackets sit inside the window opening and the blind fits within the frame. Trim and moulding stay fully visible, and the blind looks like part of the window. Because the blind has to be slightly narrower than the opening so it can move freely, a thin gap of light shows at each side.

What is an outside mount?

With an outside mount, the blind is fixed to the wall or the face of the trim and extends past the opening on each side and above it. It covers the frame and overlaps the glass, so less light gets in at the edges. Mounting higher and wider can also make a small window look bigger.

Which mount blocks more light?

An outside mount generally blocks more light, because the blind overlaps the opening instead of sitting inside it. That makes it the usual choice for bedrooms, nurseries and media rooms, especially with room darkening roller shades or blackout zebra blinds.

Is your window frame deep enough for an inside mount?

An inside mount needs enough depth in the frame for the headrail or roll to fit and for the blind to clear handles and cranks when it moves. The depth needed varies by product: a slim roller shade needs less than a larger roll or a slatted blind. To check, measure from the front edge of the frame back to the glass, or to the nearest crank or handle if that is closer, and bring that number to your consultation. If the frame is shallow or the window has protruding hardware, an outside mount is often the answer.

Things to check before you choose

Look for crank handles, locks and alarm sensors that the blind must clear. Check whether the window is square, because inside mounts on uneven frames can show uneven gaps. Note anything around the window, such as a counter, a radiator or furniture, that limits an outside mount. And decide whether you want to show off the trim or cover it.

How to measure for custom blinds

For an inside mount, measure the width inside the frame at the top, middle and bottom and use the narrowest, because the blind has to fit the tightest point. Measure the height at the left, centre and right too, because few windows are perfectly square. For an outside mount, decide how far past the opening the blind should extend and measure the area you want covered. Note the frame depth either way.

With custom blinds, a small measuring error can mean a blind that does not fit. That is why Golden Frames measures every window during a free in-home consultation and confirms the mount with you before anything is ordered. If you are preparing for a visit, our guide to making the most of your consultation explains what to have ready.

Frequently asked questions

Can I use both mounts in the same room?

Yes, but matching the mount across windows in one room usually looks more consistent. Mixing makes sense when one window has a shallow frame or obstructions.

Which mount is better for zebra blinds?

Both work. Inside mounts suit living spaces where the trim is a feature; outside mounts suit bedrooms where edge light matters. See zebra blinds for more on the product.

Book a free measuring and consultation visit in St. Thomas, London, Aylmer or across our service areas, or compare every product in our window coverings guide. The room photograph with this guide is an illustrative design concept. Written by Golden Frames, a family-owned window coverings business based in St. Thomas, Ontario.