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How to Measure Scope Height Correctly [Complete Guide]

How to Measure Scope Height

There are some doubts and questions that arise when determining how to measure scope height appropriately.

I remember buying the wrong scope rings because I couldn’t figure out what height I needed. You don’t want to make the same mistake!

I’ll resolve any confusion you may have as this article will guide you through everything you need to know, along with the following:

  • Top techniques and steps on how to measure scope height
  • How to make your money and trip to the store worth it

Measuring Scope Height


Let’s go into the details of how to measure rifle scope height.

Bear in mind that different rifle scopes need different ring heights, so scope height isn’t a “one for all” kind of thing.

For example, a bigger tube size would need rings. Specialized scopes for long-range ones would require the right MOA bases.

A long-distance rifle would need adjustable MOA bases which would require different types of rifle scopes.

Objective Lens

What can primarily help in determining the proper scope ring height would be the objective lens.

Commonly referred to as “bell housing”, the lens is the widest portion of a rifle scope body found on the opposite side of it.

The average size of objective lenses measures 40mm. This or the 42mm offers the optimum optical clarity and light transmission.

The rule of thumb to determine the mount height and ring height can be done in 2 ways. Here is the first way:

  1. Measure the objective lens diameter. This is usually in millimeters.
  2. Add 2-4mm to account for the thickness of the scope’s body.
  3. Divide the sum into two; this would give you your scope ring height measurement

The second method is to measure your scope tube diameter.

Note the objective diameter and divide it in half. This figure is not the exact measurement but it can help in figuring your scope ring height.

Most manufacturers would indicate the directions, specific measurement, and base ring system required for the particular scope. 

Measuring Scope Ring Height

The majority of manufacturers create a base measurement that is specific to a certain receiver.

A Dovetail base, for example, would only fit Dovetail rings, naturally. It is important to note that the base height would add to the overall ring height.

Check out my list of the different types of scope mounts to learn more!

Bases can come in one or two pieces. They help soften recoil forces and contribute to the ease of loading and unloading the guns.

Meanwhile, there are two types of scope rings: vertically split and horizontally split rings.

In my experience, the former is more challenging to install.

The vertically split rings; however, call for a stronger mount. When installed, they are fully embedded on the scope tube.

On the other hand, I find horizontally split rings are easier to mount. The base already has half of the ring structure.

Plus, the mold of the ring makes it easier to even out the gaps during installation.

Other Things to Consider When Measuring Scope Height

Sight height, also known as height over bore, is necessary to help calculate your scope ring center line in setting up your rifle.

For sight height or height over bore, my approach is to measure the distance from the barrel’s center to the center of the scope body or scope rings.

Bolt length would also affect the height of rifle scopes as much as the ring center line would.

For instance, one cannot mount a scope too low if it is long. The shooter would need some space to maneuver and reload the rifle.

In addition, rifles with additional accessories such as open sights and iron sights would consequently adjust the scope distance.

Importance of Having the Right Scope Height


The scope ring height ultimately affects the rifle’s precision when using the scope.

If the scope rings are mounted too high or too low, this would have a detrimental impact on the accuracy.

In my experience, my comfort was also compromised while using the installed optics. I’ll explain this more later.

A lot of factors can affect the required scope ring height – range shooting of rifle, target size, model or type of scope, and even the scope tube size. 

However, when it comes to precision shooting with the scope, one thing remains the same – optics should be mounted as low as possible.

This means that the scope should be mounted at the LOWEST possible height that isn’t in contact with any portion of the rifle or the barrel.

This also applies when using scopes with red dot sights on top.

The reason for this is because a lower scope height makes it closer to the bore axis of the rifle.

The lower the scope it is mounted, the more consistent and accurate it is to the sight picture.

I found that this set up is extremely suitable for long-range shooting! That is my general rule when it comes to mounting a scope.

A higher scope ring height is only preferred when there are particular objectives required or tactical strategies involved.

Comfort Level Affects the Scope Height

It is important to achieve the right height of the scope as this also contributes to the ease of use of the firearm.

Most rifles have a low cheek rest or comb which is why a lower scope ring height would be highly preferred.

When a scope is mounted, you should be able to place or rest a portion of their cheek or at least the bottom of their chin to the top of the rifle comb. 

As a result, it would be EASIER to look through the optic. 

If there’s a gap between the shooter’s cheek and the comb, this means the scope is mounted too high.

Remember that and let that information sear itself on your brain when using your scope.

This is often called a chicken-necksituation with the scope.

Not only would it be difficult for the shooter to use it, but this might also cause inaccuracy when shooting while using the scope.



This next portion sounds like a science topic but it’s crucial for any shooter to understand. Bear with me for a moment. 

The rifle scope height is important since it should take into account the trajectory of a hunting bullet.

The line of sight perceptible from the optic comes as in a straight line, meaning that the light travels in a linear direction.

In a nutshell, this is how our vision works! But don’t feel bad for this limiting aspect. If The Punisher could do it, so can you.

However, when it comes to bullets, it has a trajectory and travels in a direction similar to a loop.

Thus, instead of a straight line, it goes to a downward curve. Gravity plays an important part in this.

Aside from external conditions that may further derail the journey of a bullet, GRAVITY is the main cause that affects the bullet drop rate.

This is usually mitigated by the barrel which slightly points up.

This design in the barrel would offset the projected trajectory in such a way that when the bullet reaches the object, it would meet the line of vision seen in the reticle center.

Frequently Asked Questions

What is the Standard Scope Height?

Most AR-15 rifles come at a standard height of 1.5 inches. This height gives you a comfortable enough position to shoot.

What is the Cleaning Rod Method?

The cleaning rod method is another way of determining scope height.

It involves removing the bolt of your firearm and using a cleaning rod to get to the centerline of the barrel.

From there, you can get the scope height by measuring distance between the center of the cleaning rod and the center of the scope or scope rings.



There is no fixed way or procedure to measure the correct height of scopes that would be applicable to all gun products.

A lot of things have to be considered.

Aside from knowing measurements, other factors that would affect how to measure scope ring height would be the ring center distance, bolt clearance, and presence of accessories.

I hope this guide will help you get the job done!

FINAL TIP: For more information on riflescopes, I recommend you thoroughly go through our Beginner’s Guide on How Riflescopes Work to help you out.

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