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What Do the Numbers on a Scope Mean? [Guide for Beginners]

What Do the Numbers on a Scope Mean

I understand it can get confusing to see so many numbers on a product name.

When I was a beginner, every rifle scope I bought had so many numbers that I didn’t understand what they meant.

But you still can’t overlook them!

These numbers are important for you to learn to become a better shooter. Learning what they meant saved me A LOT of time and effort.

If you’re a beginner and have limited knowledge about the numbers on a rifle scope, this guide will help you out.

What Do the Numbers Mean on a Rifle Scope?

The numbers on a rifle scope may look a bit tricky at the beginning, but they are a piece of cake to read with the naked eye when you finally understand how they work.

A good example would be a mid-range variable power scope with this number written on it:

3 – 9 x 40mm.

These numbers show three things:

  • The 3 is the minimum rifle scope magnification
  • The 9 is its maximum scope magnification
  • The 40 mm represents the diameter of the objective lens

In this example, the scope magnification range is 3 to 9x.

Since the numbers range from 3 to 9, the scope can be zoomed between 3x and 9x magnification.

Still having trouble understanding the numbers?

In the same example of a 3 – 9 x 40mm rifle scope, this is what we can make out of the numbers:

  • Lower magnification – It has a minimum zoom range of 3x magnification
  • Upper magnification limit – The zoom range is adjustable up to 9x magnification
  • Objective lens diameter – It has a 40mm objective lens diameter

Let’s go even DEEPER and focus on how each number affects performance. Taking the same example of 3 – 9 x 40:

3 – 3x or three power, the minimum magnification for this particular scope. The target object will look three times larger than it does with the naked eye.

9 –9x or nine power. This represents the maximum zoom range of the scope. The target object will appear nine times nearer than it does with a naked eye.

40 – 40mm objective lens diameter, which is responsible for the amount of light entering the scope. The more light that enters, the CLEARER the sight picture.

Types of Rifle Scopes

Not all rifle scopes are the same, so you might be confused when you see numbers that look different from the example we gave above.

You have to familiarize yourself with the two main types of scopes (fixed and variable power scopes) to understand what the different numbers mean:

Fixed Power Scopes

Fixed Power Scopes

A fixed power scope is a rifle scope that has a FIXED or NON-ADJUSTABLE magnification setting.

These scopes features a magnification range from as low as 2.5x up to a fixed 20x power, depending on the scope model, of course.

A fixed scope will only show a number like 6 x 45mm, wherein the first number displays the fixed magnification of 6 and the second number shows the diameter of the ocular lens.

Variable Power Rifle Scopes

Variable Power Rifle Scopes

Variable power scopes feature a magnification range that can be adjusted from one power to another.

The magnification adjustment is done with a power adjustment ring located on an eyepiece that rotates.

The eyepiece is marked with numbers that correspond to the variable magnification (e.g., 3x – 9x — with 3x being the minimum magnification and 9x being the maximum magnification).

Some lower power scopes have a very low magnification (1-6x) while some high power scopes can go up to 25x!

I prefer a variable magnification scope as it can cover a broad range of shooting and hunting scenarios.

Choosing the Right Scope Magnification Numbers

Magnification numbers on scopes are obviously important when choosing a scope.

They simply show HOW FAR your rifle scope can zoom in and out.

However, HIGH magnifications are not always necessary. Here are a few factors to consider when reading magnification.

1. How Far Can You See?

Sight icon

The main purpose of knowing the magnification numbers on a rifle scope is to know how far you can see.

To put it mathematically, let’s try an example. Imagine seeing a target that’s 90 feet away.

A 3x magnification will make it look like it’s 30 feet away. Whereas using a 9x magnification will make the target appear only 10 feet away!

The higher your magnification, the CLOSER you are to the target.

2. Adjustable Magnification/Zoom Range

Magnification icon

Fixed magnification scopes have a static magnification, which means you can’t zoom anymore than it’s already magnified.

Ask yourself if you need this for your hunting or shooting scenarios. If not, maybe variable scopes are better for you.

3. Bigger Numbers Aren’t Always Better

Thumbs down icon

When I was a beginner, I often believed that I needed a scope with the highest magnification possible. 

Don’t make the same mistake. What are you going to do with such a large scope?

Zooming too far can lead to various distortions that negatively impact your accuracy.

Instead, choose a rifle scope that lets you see clearly for only the effective distances you need.

Other Important Numbers on the Rifle Scope

Other Important Numbers on the Rifle Scope

Magnification isn’t the only to consider when choosing a scope.

There are other specifications you should familiarize yourself with before making a purchase:

Scope Tube Diameter

This helps you select the rings for fitting the scope onto the rifle.

You can often see this on the box or manual of the scope.

The most standard scope tube diameter is 30 mm, but you can also find tube sizes that are 1 inch and 34 mm.

These tubes allow light to pass through in a wider area, making them useful for a larger range of elevation adjustment and higher resolution on scopes.

Field of View

The normal field vision of a human iris is around a 210 degrees horizontal arc in front of your naked eye.

When you begin to FOCUS on an object to identify its features, the field of view gets smaller.

Scope magnification ranges work in a similar way.

When you focus on your targets at a distance, the field of view gets smaller.

Most scopes list a field of view parameter at different ranges to help you gauge the difference between them.

Things to note:

  • Bigger rifle scope lenses allow a wider field of view than smaller lenses.
  • A bigger FOV is better for acquiring targets or even moving targets.

Therefore, hunters prefer scopes with a larger FOV. But, if you’re just a beginner, I recommend starting small!

Elevation and Windage Adjustment

The scope’s windage and elevation determine how much you can adjust the reticle to the left and right or up and down on a rifle.

The adjustments are typically given in MOA or MRAD, and in some cases, in millimeters.

A rifle with a windage specification of 2.5 m/100 m means that you can adjust the reticle 1.25 m to the right or 1.25 m to the left for a target at a distance of 100 m.

If the scope comes with an elevation adjustment of 2 m/100 m, then the reticle can be adjusted 1 m up or 1 m down for a distance of 100 m.

Minute of Angle (MOA)

MOA is used in shooting over very long distances to measure the average point of impact of a bullet.

It determines how much your bullet DEVIATES over a given distance and is measured in inches.

Here are examples to further explain this:

Let’s say you shoot your rifle 5 times into a 100-yard single target, and every bullet hits within a one-inch circle on the target.

You could say that your rifle is at a 1 MOA.

If you were long-range shooting at a target that is 200 yards away and bullets hit within a 2-inch radius, then your rifle would still be at 1 MOA.

Therefore, hitting a 10-inch group at a long range of 500 yards can be calculated as 2 MOA.

Milliradian (MRAD)

The Milliradian or MRAD determines the angle bullets need to travel to hit a given target.

When bullets are shot over longer ranges, they travel in a CIRCULAR rather than a straight line.

The farther they go before hitting the target, the bigger the circular arc they travel.

This circular arc that the bullets travel is measured in MRAD.

Eye Relief

The eye relief shows how far away your eye needs to be from the eyepiece to get a full field of view.

Basically, if your eye was right next to the rear lens or ocular lens of your sniper rifle scope, then eye relief is the distance you need to back away so that the full field of view is visible.

Size of the Objective Lens

The objective lens size has a significant effect on your shot.

A larger objective lens with a larger diameter is preferable to smaller lenses. Why? Because a larger objective lens allows MORE light to enter the scope.

This results in a significantly brighter and more detailed image, which is especially important when shooting in conditions with insufficient light.

Exit Pupil of a Magnification

The exit pupil refers to the diameter of how much light travels through the rifle scope.

The exit pupil should be between 2mm to 9mm. A very small exit pupil isn’t good enough to make the image bright and clear.

The larger the exit pupil, the better it will be in low light conditions.

You can calculate the exit pupil number of a rifle scope by dividing the diameter of the objective lenses by the scope’s lower magnification power or level.

We can use this formula for this focal length as an example: 4 – 7 x 60mm.

To find the exit pupil at various magnifications, whether maximum magnification or minimum magnification, use this formula:

  • At a magnification of 4: 60 / 4 = an exit pupil of 15 mm
  • At a magnification of 7: 60 / 7 = an exit pupil of 8.57 mm 

IMPORTANT NOTE #1: The human pupil can expand to a maximum of imprecisely 8 mm in almost complete darkness. The naked eye will not perceive the entire field of vision created by the 60 mm scope lens at 4x magnification as much light enters the scope. 

IMPORTANT NOTE #2: A rifle scope does not require an objective lens as large as a pair of binoculars, as you will be zooming in on a single target and will not be viewing a large area through the scope.

Can the Scope Numbers Be Decreased?

Can the Scope Numbers Be Decreased?

Once you’ve purchased a scope, you may be wondering whether you can make changes or alterations.

I’m here to tell you that while it is POSSIBLE, none of them are really beneficial, and many of them can be detrimental to your scope.

I didn’t want to risk it, so I ended up getting a new scope instead. I suggest you do the same if you are unhappy with the scope numbers.

If you DO wish to make changes, here are some things you can keep in mind:

Chromatic Aberration

Chromatic aberration can be a serious issue for used and damaged scopes.

Without compensation for chromatic aberration, a new rifle scope can make a rainbow-like effect.

This happens when water droplets hit the lens, altering the light entering the scope.

It worsens as you zoom the scope magnification range.

Adjust the Magnification Ring

You can always adjust your scope within the provided parameters. Just twist the power ring to zoom in or out.

Be careful, though — too much magnification isn’t necessary!

Magnification Power

The scope’s magnification power affects its clarity and dimness.

Further zooming typically makes a scope less clear, especially if you did not purchase a good scope.

That’s another reason why I say too much magnification is unnecessary; setting it to the highest may make your image unclear.

The ambient lighting will also affect how well you can see through the scope — scopes designed for long-range aiming usually correct this issue.

Quick Examples

Quick Examples

Let’s test if you really understand what the scope numbers mean.

1. What Is a 4-12×50 Scope?

The 4 to 12 marking means that the scope is a variable-powered scope. The scope has a variable magnification range that starts at 4x and adjusts up to 12x.

50, on the other hand, means that the scope has a 50mm objective lens.

2. What Is the Range of a 4-12×40 Scope?

This means that a mid-range rifle scope can magnify as low as 4x or as high as 12x with an objective lens diameter of 40mm.

3. What Does 6-24×50 Mean on a Scope?

This also means variable-powered scopes magnify 6x as the lowest magnification setting.

The magnification range starts at 6x and can adjust up to 24x.

This scope has an objective lens diameter of 50mm.

4. What Is the Range of a 3-9×40 Scope?

The 3-9×50 numbers mean that the model has a power magnification range that starts at 3x and can adjust up to 9x.

The last number, 40, means that the scope has an objective lens diameter that is 40mm around.

5. How Far Can You See With a 4-12×40 Scope?

This scope’s numbers tell us that the max zoom range is 12x. This scope can provide aiming points approximately out to 500 yards.

6. What Does 12×50 Mean on a Scope?

This is the type of number you see on FIXED power scopes.

The magnification power of a 12×50 is 12 times larger than normal unaided vision.

7. What Does 40mm Mean on a Scope?

The “40mm” refers to the objective lens diameter in millimeters.

Frequently Asked Questions

Frequently Asked Questions

Is a Bigger Objective Lens Better?

Yes, in terms of performance.

The larger the objective diameter, the greater the light-collecting power. The result is a higher resolution and a brighter image.

However, a large objective lens also means a bulkier and heavier scope, which can be a downside in some hunting scenarios.

What Magnification Range Do Snipers Use?

Snipers often use a 2x-12x magnification level, which is suitable for short to long ranges.

What Magnification Scope Do Navy Seal Snipers Use?

They use scopes that are designed to shoot well within 600 yards.

It allows them enough space to make any necessary adjustments to get the best shot in various distances.

What Do the Numbers on a Spotting Scope Mean?

Reading a spotting scope is the same as reading a fixed power scope.

The first number represents the magnification and the second one refers to the diameter of the lens.

How Much Magnification Do I Need?

It depends on the kind of shooting you want to do.

For example, if your target is far away, a scope with higher magnification is ideal.

Nearer targets don’t require a high magnification, so a low power scope with a low magnification will suffice.

Choose a magnification that is appropriate for your hunting situation!

Final Thoughts

Before hitting the power range, it’s vital to understand the numbers on a rifle scope.

You don’t want to come in your shooting or hunting session with a magnification that’s TOO LOW or TOO HIGH. It can make or break your shot!

As long as you understand the numbers and buy the appropriate scope, all you need to worry about now is refining your skills as a shooter.

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