Housing Height for Red Dot Sights: How to Choose Yours

How do I measure the correct Housing Height before I buy?

To determine the correct Housing Height, you must measure the available vertical space on your specific mounting surface. Identify the point where the optic will sit and measure from that surface upward to the highest point of your grip or your hand’s natural position.

Tools and measurements needed

Use a digital caliper or a standard metric ruler to measure the distance in mm. You need to find the clearance gap between the top of the rail and the top of the nearest obstruction, such as the slide, the grip, or a mounting bracket.

Locating the measurement on the product

Manufacturers typically list the housing height in the technical specifications section of the product documentation. Look for the term “Housing Height” or “Height over Bore” expressed in mm to confirm the dimension before ordering.

What happens if the Housing Height is too low or too high?

A Housing Height that is too low can cause the optic to sit too close to the barrel or the grip. This often results in the optic housing physically striking the slide during the cycling of the action or preventing the user from maintaining a proper grip.

Consequences of a low Housing Height

If the housing height is insufficient, the optic may block the movement of the slide or the ejection port. It can also result in the optic being so low that it interferes with your hand’s ability to wrap around the grip, compromising safety and control.

Ensure your mount is compatible by checking the correct thread pitch.

Consequences of a high Housing Height

A Housing Height that is too high moves the optic further away from the bore line. This increases the distance between your eye and the glass, which can make it harder to align the reticle with the target and may result in a less natural-feeling sight picture.

What should I do if I fall between two Housing Height values?

When your measurements suggest a value that falls between two standard options, you should prioritize clearance over a low profile. It is safer to have slightly more space than to risk the optic interfering with the movement of the firearm or your grip.

Choosing the larger value

If you are between two sizes, select the higher Housing Height. This ensures that you have enough room for the optic to function without physical interference. A slightly higher optic is easier to correct for than an optic that cannot cycle properly or prevents a secure grip.

Confirming local regulations

Before finalizing your selection, confirm the current rules for your specific location regarding optic types and mounting. Regulations can vary by state or city, so verify your local requirements before placing an order.

Reviewed by the RecommendedOptics editorial team. RecommendedOptics writes these guides from the 200 most-reviewed red dot sight listings in our retail dataset, not from manufacturer copy.