How to Measure Shutters for an Outside Mount Window
This guide walks you through measuring for shutters mounted outside your window opening, on the surrounding wall, trim, or molding.
Outside Mount shutters are fixed to the surface around the window rather than inside the opening itself, to create a fully framed look.
Follow the steps below and take your time. If you’d like a second set of eyes before your order goes into production, opt in to our free Design-Check at checkout.
What is an Outside Mount?
An outside mount means the shutter frame is fixed to the wall or trim around the interior window rather than inside the opening. This is typically the right choice when:
The window doesn’t have enough depth inside the opening for an inside mount
Your chosen slat size doesn’t have enough clearance to open and close properly
The window opens inward, and you want to keep that function
The window sits flush to the wall with no recess (such as a sash window)
For an outside mount to work, you’ll need a flat surface to fix the frame to. That could be:
The wall directly around the window opening
Flat window trim or molding
The area just outside the trim, if the trim is decorative or uneven
What is a shutter frame?
The frame holds your shutter panels in place and creates a level, square surface to hang them from. Because most window openings aren’t perfectly square, the frame also makes it much easier to get a clean, professional-looking installation. Most of our frames come pre-drilled for easier installation.
How many frame sides?
Full Height & Tier-on-Tier and Café Style.
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Full Height & Tier-on-Tier | Café Style |
All four sides are recommended for maximum stability. | 3 sides (left, right, bottom) |
What you’ll need
Steel tape measure
Pen and paper
Printed frame templates
Step 1: Decide where your frame will sit
Before you measure, choose exactly where the frame will be mounted.
Important: If you're mounting outside of the trim and would like advice, please contact our shutter experts
There are three options:
Mount on the wall, Mount on the trim, Mount outside the trim.
Step 2: Choose your slat size and frame depth
Before measuring, make sure your window has enough clearance for the louvers to open and close freely. Measure how far any obstructions project out, such as handles, locks, sensors, or trim, and check against the table below. Your frame depth must clear these.
Slat Size | Depth Requirements |
2 ½” | 1 ⅞” |
3” | 2 ¼” |
3 ½” | 2 ⅜” |
4” | 2 ⅝” |
4 ½” | 3” |
Tip: If space is limited, a smaller slat size may be the answer. Contact us and our team can advise.
Step 3: Use a template to plan your position
We recommend printing our frame templates to scale. Place three frame template pieces per side to get an accurate picture of how the frame will sit. Include the templates in your measurement.
Templates help you:
Visualize the final size and position
Check for obstructions before ordering
See how far the shutters will project into the room
Important: Your final measurements must include the full width of the frame. We do not add the frame width for you.
Step 4: Measure your width
Measure across the full area where the frame will sit, including the frame templates if you’ve positioned them.
Take measurements at the top, middle, and bottom
Use the largest measurement when ordering
Measure to the nearest 1/8"
Important: Unlike inside mount, outside mount uses the largest measurement to ensure full coverage.
Step 5: Measure the height
Measure the height of the area where the frame will sit, including the frame templates if you’ve positioned them.
Measure at the left, center, and right
Use the largest measurement when ordering
Measure to the nearest 1/8"
Tip: If you’re measuring side-by-side windows, use the same height for all shutters. Even small differences can affect panel layout and make the shutters look mismatched once installed.
Step 6: Mid Rail and T-Bar
Mid Rail
A mid rail is a horizontal divider that runs across the middle of your shutters.
A mid rail is required if your shutters are over 62" tall
This is optional if your shutters are between 38" – 62"
To measure for a mid rail, measure from the bottom of the opening to where you want the center of the rail to sit.
Note: We may adjust the mid rail position slightly during production to align cleanly with the slat spacing. If you need the mid rail in an exact position, please contact us before placing your order.
T-Bar (Tier-on-Tier only)
A T-bar is the horizontal frame piece that separates the upper and lower panels on a Tier on Tier shutter. If you’re ordering Tier on Tier, you’ll need to provide a T-bar position.
To measure for a T-bar, measure from the bottom of the opening to where you want the center of the T-bar to sit.
Café Style
To measure for a Café Style shutter, measure from the bottom of the opening, up to where you want the shutter to finish.
Step 7: Final checks
Your measurements must include the full frame width and height; we do not add this for you.
Always submit your exact measurements to 1/8”. Do not round up or down.
Double-check clearance depth for your chosen slat size.
Not sure if your measurements are right? This guide is designed to help you measure with confidence. If you’re ever unsure, position your templates and send us a photo by email or live chat, and our team of shutter specialists will check everything before you order.
Important: Incorrect measurements can result in fitting issues. If you’re at all unsure, contact us and our customer service will be happy to help.