Scope Numbers Meaning in Riflescopes, Revealed!

Rifle scopes are innovative sighting tools to take advantage of to see your targets clearer and as if they’re closer to you. However, have you ever wondered about the scope numbers meaning? Here’s what to help you figure them out so that you can adjust your scopes accordingly or choose one based on your needs.

Most important scope numbers: If you’re buying a rifle scope, you’ll normally see two of the most significant numbers that matter; the first one being the magnification (X) and the second one being the size of the scope (mm).

These numbers are related to the sighting device’s thickness, curvature, and diameter. But aside from them, you’ll find other numbers that pertain to the eye relief, field of vision (FOV), tube diameter, elevation and windage, and more.

Magnification and Power (X)

Before buying your first riflescope, understand its power or magnification, which is indicated by “X.”

For example, a scope with 4-12X40mm means that the unit has a minimum of four times magnification and maximum of 12 times magnification. On the other hand, 40mm pertains to the diameter size of its lens.

From this example, it means that you’ll be able to see targets from four to 12 times more than what your naked eyes can allow.

So, if you’d set the scope at four times with your target at 400 yards away from you, the scope will deliver you an image as if it’s only 100 yards away. But if you set the magnification setting at a higher power, you will see the target closer – up to 12 times.

This is the case for variable scopes.

But then, there are also fixed power scopes that you need to take note of. For instance, a scope showing a number of 1x30mm indicates the lens has a fixed zoom of one time and the 30mm represents the size of the lens diameter.

How to go about choosing your magnification? All you need to remember is that the target will seem larger as you increase the magnification setting.

However, you’re probably thinking that the higher magnification will always be better. This is not the case, though. Remember, as the magnification becomes higher, the smaller your FOV will become.

So this means that a greater power doesn’t always translate to a better riflescope.

An optic with 3-9X or 4-12X may still be the better choice because they can virtually cover most of the situations that beginners and average shooters will find themselves into.

Summing this section up, choose a riflescope with a magnification, which is sufficient to help you see your target clearer. And in most cases, too much power comes with specific downsides regarding distortion, complexity, and limited field of view.

Typically, hunters and shooters prefer a max of 10X magnification when aiming for targets out to up to 500 yards away. Meanwhile, other hunters would go for scopes with between 4X and 6X power particularly because they target within a distance of between 100 and 200 yards away.

Objective lens size (millimeters/mm)

The number that comes after power indicates the lens size or diameter noted in mm. It’s the lens that is closest to the target.

A riflescope with a larger lens will allow more light that the scope can draw in, while also allowing the shooter to focus easily.

A larger objective lens is valuable especially when shooting in low light situations and in dusk, dawn, or cloudy days. It can offer you a brighter and clearer view of an image.

For example, a 4-12X40mm scope will allow you to see brighter in the zoom settings than what a scope with 4-12X32mm can provide you with.
Typically, you’ll find sighting devices ranging from 30mm to 44mm, but still, there are larger models with objective lens sizes as big as 50mm or even 80mm.

Meanwhile, you’ll also find scopes with adjustable objective lenses (AO lenses), allowing users to choose between different diameters based on the situation.

Picking the right lens size? To help you compare your options, consider the right lens size for the appropriate mounting position.

The size of the objective lens can give you a clear picture as to the manner that the scope’s going to mount on your firearm.

A scope with a larger objective will have an equally larger objective bell. A too large objective can interfere or obstruct the mounting position, while also determining the clearance of the scope.

You also have to buy higher mounting rings to keep the bell off the barrel of the firearm, resulting in much discomfort and poor eye alignment, while also compromising the cheek and weld method’s repeatability.

A midrange or smaller sized objective diameter gives a lower profile, while also helping you achieve a fast and easy eye alignment and consistent cheek and weld method. Using a smaller objective scope also allows you to buy and use standard mounting rings.

Weight of the scope – a larger objective lens will add more weight to the riflescope’s overall weight, making it awkward and heavy to carry for hunting long hours.

Opt for a standard 40mm lens size if you don’t want more bulkiness and more weight. But if you’re okay with some more bulk, you can also go for a 50mm lens.

Elevation and windage (mm)

You can find the windage turret sitting on your scope’s side. It lets you adjust for the reticle’s horizontal alignment in order to adjust the point-of-impact for wind.

On the other hand, the elevation turret is on the top of the body of your scope. This offers the vertical adjustment of your reticle, adjusting for bullet drop to your target.

These adjustments, which are measured in millimeters, let you identify how much you can adjust for the travel path of the bullet up or down as well as left or right, based on the shooting environment. Adjusting any of them will need only turning the scope’s knobs or dials.

Field of view (FOV)

It’s the size of the area that you can see through your riflescope’s lens. You’ll see a larger field of view with a scope that has a bigger lens. It is also more useful if you’re tracking a moving target.

Horizontally, your field of vision is at 210 degrees (human eyes), but it’ll be reduced as your target fills the area when you zoom in using your scope.

So if you’re using a sighting device with a rating of 100 feet at 1000 yards, it means that you can only view the 100th of your 210 degrees at a full magnification.

Exit Pupil (mm)

It’s the light beam’s width that leaves your eyepiece and is measured in millimeters. You will see a brighter image with a scope having a larger exit pupil even in low lighting conditions.

Eye Relief (inches)

It’s the distance between the scope’s lens to your eye’s tips. With the wrong distance of eye relief, a shooter will see a distorted image, which can be fuzzy or have a black ring around the field of view.

You need to consider the eye relief of a scope, which must be long and generous enough especially if your firearm has heavy recoil. Avoid scopes with a short eye relief because it can increase the risk of an injury.

Most scopes will typically have eye relief between 3.5 to 6 inches.

A longer eye relief allows more space between the eyepiece and your eye, while still delivering view accuracy.


It’s the reticle’s level of movement in relation with your target image. It is also the view inconsistency that you can see when looking down your riflescope, causing the crosshair to move across your target when changing or shifting the position of your eyes.

In scopes, if you are to move your eye toward any side with the crosshairs remaining the same on your target, your scope is parallax-free, but there is a parallax error if you shift your head with the scope still and the reticle becomes off the target.

This error happens with higher powered scopes.

At the very least, riflescopes should be parallax-free from at least 15 yards up to 150 yards. On the other hand, there are brands that offer side focus adjustments, helping shooters compensate for errors at a long distance.

There you have the scope numbers meaning and what you need to know about them as important elements that contribute to how your riflescope performs. Hope you learn a thing or two from this post. And don’t forget to share it on social media to help friends looking for the same information today!

Related Post: