Mount Height for Riflescope Mounts: How to Choose Yours

How to Measure and Establish Your Mount Height

Establishing your required mount height begins with identifying the physical dimensions of the optic you intend to mount. Most manufacturers list the “height above rail” or “body height” in the technical specifications of the optic itself.

Locating the Spec on the Optic

Check the manufacturer’s datasheet for the height of the optic’s center point relative to its base. This value is the baseline from which you calculate the necessary mount height. If the optic is 30mm tall, the center point is roughly 15mm above its own mounting surface.

Calculating Eye Relief and Cheek Weld

Your physical posture determines the final height. To find the correct value, place the optic on a mock-up mount (or a temporary rail) and simulate your shooting position with your rifle stock. Move the optic up and down until your eye is positioned at the manufacturer’s recommended eye relief distance—usually 2 to 4 inches behind the eyepiece.

Understanding your rail system is vital, so learn about compatible rail interface types before purchasing.

Measure the distance from the top of the receiver to the center of the optic’s bore in this position. This measurement, in millimeters, is the mount height you must order. If you are using a cheek riser, this measurement will decrease because the riser brings your face closer to the optic.

The Risks of Incorrect Mount Height

Choosing a mount height that is too low or too high creates mechanical and ergonomic issues that can compromise accuracy and comfort.

Consequences of a Mount Height Too Low

A mount height that is too low often results in poor eye relief. If the optic sits too close to the receiver, you may have to lean your head forward or “crouch” into the stock to see the full reticle. This puts strain on the neck and can cause the optic to block your view of the target.

In some cases, a mount that is too low may cause the optic’s body to physically interfere with the rifle’s ejection port or the charging handle. This can prevent the action from cycling correctly or cause the optic to strike the bolt as it moves.

Consequences of a Mount Height Too High

A mount height that is too high moves the optic further away from the shooter’s face. This forces the shooter to pull their head back, potentially resulting in an uncomfortable cheek weld where the cheekbone rests too high on the stock. It can also lead to “parallax” issues where the shooter’s eye is not perfectly aligned with the center of the optic.

Furthermore, excessive height increases the leverage exerted on the mount. Because the optic is further from the rail, recoil can cause the mount to flex or “cant” more easily, which may lead to a shift in the point of impact over time.

Matching your hardware correctly is essential, so find the right tube diameter specifications for your optic.

What to Do if You Fall Between Two Mount Heights?

If your measurements place you between two standard mount heights, such as 30mm and 35mm, you must choose a direction based on your specific hardware.

The Rule of Clearance

When choosing between two values, always prioritize the height that provides enough physical clearance for the optic’s body. If an optic is large, it is better to have slightly more height than needed than to have an optic that physically hits the receiver or the forend of the rifle.

Prioritizing the Cheek Weld

If the optic has plenty of clearance in both height options, choose the lower of the two values. A lower mount height generally allows for a more natural and consistent cheek weld. A consistent weld is the foundation of repeatable accuracy, as it ensures your eye returns to the exact same spot every time you lift the rifle to your face.

If you find that the lower option still provides adequate eye relief, it is the technically superior choice for a reliability-first setup. If you find the lower option provides poor eye relief, you may need to consider a cheek riser in addition to the higher mount height to bring your face up to the optic.

Local Regulations

Confirm the current local rules and regulations regarding rifle accessories in your specific location before ordering. Requirements for certain types of optics or mounting hardware can vary significantly by country, state, and city.

Reviewed by the RecommendedOptics editorial team. RecommendedOptics writes these guides from the 19 most-reviewed riflescope optic mount listings in our retail dataset, not from manufacturer copy.