Choosing inside mount vs outside mount sounds like a small detail when ordering custom window treatments. It's not. The two approaches use completely different measuring rules, and if you pick the wrong one, every number you recorded needs to be redone. Getting the mount type right before pulling out the tape measure is what separates a clean custom order from a frustrating one. The good news: two quick checks are all it takes.

Inside Mount vs Outside Mount at a Glance

	Inside Mount	Outside Mount
Where it installs	Inside the window frame	On the wall, outside the frame
Minimum frame depth required	2.8 inches	None
Visual effect on window size	No change	Appears larger
Best for	Clean look; decorative frames	Small windows; blackout; hiding wall flaws
What you measure	Interior frame dimensions	Desired wall coverage area

What Inside Mount and Outside Mount Mean

Inside mount vs outside mount window treatments differ in one fundamental way: where the hardware attaches.

Inside mount places the blinds, shades, or curtain track inside the window frame opening. The product sits within the frame itself.

• The treatment blends with the frame for a clean, built-in appearance
• Decorative frame details (wood trim, stone surrounds) stay fully visible
• A natural fit for minimal interiors where the window treatment should recede into the background

Outside mount attaches the rod, track, or bracket to the wall above and outside the window frame. The treatment covers the frame and some of the surrounding wall.

• Creates a fuller, more substantial look
• Makes the window appear larger
• Covers imperfections around the frame: uneven paint, gaps, wall damage
• The standard setup for fabric curtains hung on a rod

The mount type you choose affects your measurements, your final product size, and the physical conditions your window needs to meet. Style is only part of the picture.

How to Know Which Mount Type Your Window Needs

Two quick checks will point you to the right answer.

Check Your Window Frame Depth First

Inside mount has a hard physical requirement: the frame needs at least 2.8 inches of clear depth from the glass surface to the front edge of the frame. Some products need more.

How to measure depth: Use a tape measure to check the distance from the glass (or window stop) straight to the front edge of the frame. Check a few spots, as depth can vary slightly across the frame.

What happens if depth is too shallow: The product sticks out past the front edge of the frame. Many buyers run into this on their first custom order, and it is the root cause of the "inside mount shade not fitting flush" problem. A shade that protrudes can also block the window from opening and closing correctly.

The rule: Under 2.8 inches, go with outside mount only. At 2.8 inches or more, move to the second check.

Match the Mount Type to Your Actual Needs

Situation	Recommended Mount
Want a clean, minimal look	Inside Mount
Frame has decorative value (wood, stone)	Inside Mount
Need to cover wall flaws or uneven paint around the frame	Outside Mount
Want maximum light blockage	Outside Mount
Bedroom or nursery blackout priority	Outside Mount
Fabric curtains on a standard rod	Outside Mount

Inside or Outside Mount for Small Windows

Small or short windows are the most common use case for outside mount. Here is the standard approach:

• Extend the rod or track a minimum of 4 inches beyond the frame on each side
• Mount the hardware a minimum of 6 inches above the frame, closer to the ceiling

That stretches the visual footprint of the window in both directions. Compared to inside mount on the same window, outside mount can increase the perceived window area by roughly 20–30%.

Inside mount on a small window does the opposite: it draws attention to how small the opening is rather than working around it.

How to Measure for Inside Mount vs Outside Mount

Most ordering mistakes happen at this stage. The two mount types use completely different reference points.

Measure for Inside Mount

You are measuring the interior of the frame, not the outer dimensions.

Width:

• Measure at the top, middle, and bottom of the frame opening
• Record the smallest of the three numbers (frames are rarely perfectly square)

Height:

• Measure on the left side, center, and right side
• Record the largest of the three numbers

Key note: Most custom window treatment brands automatically subtract a small deduction (around ⅛ inch) from inside mount width so the product fits cleanly into the frame. You do not need to subtract anything yourself. Enter your actual frame measurements and confirm with your brand that this deduction is applied automatically.

Measure for Outside Mount

You are measuring the wall coverage area you want, not only the frame.

Width:

• Measure the widest part of your window frame
• Add a minimum of 4 inches on each side for blinds and roller shades
• More overlap means better light control and a bigger visual effect

Height:

• Measure from where the rod or track will mount down to where you want the treatment to end
• Standard: ½ inch from the floor for a clean break, or full floor-length for fabric curtains
• For the best room-height effect, mount the rod a minimum of 6 inches below the ceiling

The core difference: Inside mount measures the space inside the frame. Outside mount measures the wall area you plan to cover. Mixing up these two starting points is the most common reason custom orders come back with the wrong fit.

Special Cases and What to Check Before You Order

Can You Mix Mount Types in the Same Room

Yes. A room with different window sizes or varying frame depths does not need a single mount type throughout. A standard window with sufficient depth can use inside mount while a shallow-framed window or wide sliding door uses outside mount. Check each window on its own merits, then step back and confirm the overall look feels consistent.

What to Do If You Are in a Rental

Both mount types involve drilling: inside mount goes into the window frame, outside mount goes into the wall. While traditional mounts require drilling, Joydeco’s No-Drill collection offers a damage-free alternative for renters who want the custom look without losing their security deposit..

When Your Frame Depth Is Right on the Edge

If your depth measures under 2.8 inches, lean toward outside mount. Pushing an inside mount into a borderline frame almost always results in the shade sticking out past the frame edge, which affects both appearance and function.

Pre-Order Checklist

Confirm these four things before placing any custom order:

1. Frame depth measured and confirmed (≥2.8 inches for inside mount, or outside mount selected)
2. Mount type chosen and measurement reference point clear (frame interior vs. wall coverage)
3. Mounting height decided, especially for outside mount
4. Product page instructions reviewed for how that brand handles the deduction, and customer service contacted if anything is unclear

Measure Once, Order Right

Two things cause custom window treatment mistakes: picking a mount type your window cannot support, and measuring from the wrong starting point. Now you have both covered. Check your frame depth first, then measure from the correct reference for the mount type you chose. Joydeco's custom shades and curtains include step-by-step measurement guides for both inside and outside mount, so you can verify every number before submitting your order.

FAQs about inside vs. outside mount

Q1: Can you install inside mount shades on a window with a shallow frame?

Technically yes, but the shade will extend past the front edge of the frame. That is what causes the "inside mount shade not fitting flush" problem. Beyond the appearance, a protruding shade can also prevent the window from opening fully. For any frame under 2.8 inches deep, outside mount is the practical choice.

Q2: Does outside mount make a window look bigger?

Yes. By extending the rod or track at least 4 inches on each side and mounting it close to the ceiling, outside mount can increase the perceived window area by roughly 20–30%. It is the most effective visual approach for small or awkwardly proportioned windows.

Q3: Which mount type works better for blackout shades?

Outside mount. The treatment covers the frame and part of the surrounding wall, which reduces the gaps around the edges where light slips through. For bedrooms and nurseries where full darkness matters, outside mount delivers noticeably better results than inside mount.

Q4: Do I need to tell Joydeco which mount type I chose when ordering?

Yes. Inside mount and outside mount use different sizing rules, and the order form will ask you to specify. Joydeco offers measurement instructions for each mount type. If anything is unclear, reach out to customer service before placing the order.

Q5: Can I use inside mount for curtains on a curtain rod?

Standard curtain rods are an outside mount setup: the brackets attach to the wall. Inside mount is more common for blinds, roller shades, and cellular shades. If you want the clean, built-in look of inside mount with fabric curtains, an inside-mount curtain track system is the better fit than a wall-mounted rod.