Inside mount blinds fit within the window frame for a clean look, while outside mount blinds are installed above the frame to provide better light blockage. The choice depends on window depth, desired appearance, and light control requirements.
Comparison Table
| Feature | Inside Mount | Outside Mount |
| Appearance | Clean, built-in, shows window trim | Makes window appear larger |
| Light Control | Light gaps possible on sides | Maximum coverage, fewer light gaps |
| Space Required | Needs 2+ inches frame depth | Works on any window depth |
| Privacy | Good, some edge light | Excellent, full coverage |
| Trim Condition | Requires good trim | Covers damaged trim |
| Cost | Slightly lower material | Slightly higher material |
Best Use Cases for Inside Mount
Choose inside mount when the window frame has at least 2 inches of depth and the trim is in good condition you want to showcase. Inside mount works best in formal living spaces, dining rooms, and bedrooms where a custom built-in appearance is desired. This method preserves window sills for decorative items and creates a recessed look that many homeowners prefer.
Best Use Cases for Outside Mount
Choose outside mount when window frames are too shallow to accommodate the blind hardware. Outside mount is also preferred when maximum light blockage is required, such as in bedrooms or media rooms. This method works well for covering unattractive windows or trim that needs to be hidden. Outside mount makes small windows appear larger by extending the visual area.
Cost Difference
Outside mount blinds typically cost slightly more than inside mount because they require wider blinds to cover the additional area beyond the frame. The price difference is usually modest and depends on window size and the amount of overlap needed. Installation complexity is similar for both methods, though outside mount may require additional hardware for wall mounting.
Measurement Tips
Inside Mount Measurement
Measure width at the top, middle, and bottom of the frame. Use the narrowest measurement so the blind fits. Measure height at left, center, and right. Use the longest measurement to ensure full coverage.
Outside Mount Measurement
Measure the width of the area you want to cover, then add 2 to 4 inches to ensure the blind extends past the frame on both sides. Measure height from the mounting point to where the blind should end, adding extra if mounting above trim.
How Window Depth Decides the Mount
Window depth is the first thing to check. Measure from the front edge of the frame back to the glass or the first obstruction, such as a crank or lock. Most standard blinds need about one and a half to two inches of depth to mount inside and tilt freely, and two and a half inch slats or cassette shades need more. If the depth is too shallow, an inside mount blind will stick out past the frame and look like a mistake, so outside mount becomes the better choice.
Square frames matter too. Many Houston homes have windows that are slightly out of square after years of settling. An inside mount blind in a crooked frame shows uneven gaps, while an outside mount hides them.
Getting the Measurements Right
For inside mount, measure width at the top, middle, and bottom, and use the smallest number. Measure height on the left, center, and right, and use the longest. For outside mount, add overlap to the width and height so the blind covers the frame. Our blind size calculator does this math for you and shows the size to order for each mount. If you would rather not risk an ordering mistake, a free in-home measurement and professional blind installation take care of every window.
Frequently Asked Questions
Which mount is better for blackout?
Outside mount is better for blackout because it greatly reduces the light gaps around the edges of the frame that occur with inside mount installations.
Can inside mount blinds be used on shallow frames?
Inside mount requires sufficient depth. For frames under 2 inches, outside mount is the recommended solution for proper installation.
Do outside mount blinds look custom?
Yes, properly installed outside mount blinds with adequate overlap appear intentional and can look as custom as inside mount, particularly on windows with minimal trim.
We measure and install window treatments for homes in Friendswood, League City, Pearland, and Clear Lake. Book a free in-home estimate to see samples in your own windows before you decide.
