Understanding What Do The Numbers on Binoculars Mean? | Your Ultimate Guide

Are you a nature lover who wants to enjoy the beauty and serenity of the valleys or a wildlife viewer who wants to capture the very essence of the wildlife without feeling their hot breath on your bare skin, or are you someone who lives on the water for their living?

No matter who you are among these while using your favorite pair of binoculars, you may have noticed some numbers written on the optical gadget body. Have you ever wondered what those numbers mean? If yes, then you! My friend is not the only one as many binoculars’ bearers are often confused about a particular question: what do the numbers on binoculars mean.

All of us are familiar and have heard the word “Binoculars,” and your presence on this site verifies it. But does every one of us know everything about binoculars? Whoa! Now that’s something worth questioning. Wait! Wait! Don’t worry because we will not take any exam from you to check your understanding of binoculars. Instead, we are here to give you a thorough and detailed overview of binoculars and what do the numbers on binoculars mean. So whether you are an amateur or a pro, you are going to find the answers to all your binoculars’ related queries here.

Key Highlights

  • The first number represents magnification, indicating how many times closer the object will appear.
  • The second number is the objective lens diameter in millimeters, influencing light gathering for brighter images.
  • A wider field of view number provides a broader area visible through the binoculars.
  • Calculated by dividing the objective lens diameter by the magnification, larger exit pupils result in brighter images, especially in low-light conditions.

What are Binoculars Used For?

Starting from the very basics, firstly, let’s discuss what a pair of binoculars has in its bag for you and in which ways it can prove to be a comrade of yours in your outdoor pursuits. So basically, binoculars are the optical miracles that magnify and sharpen those distant views for you so that you can get the best out of it.

  • Birdwatching: A birdwatcher in you does not want to miss the sight of a rare bird, and that’s where binoculars come into play. They sharpen that distant sight of the bird with excellent color fidelity so that you can get a magnificent view. Matchless portability, a wide field of view, and a magnification of 7X to 10X, with 8X being the best, are essential for spotting and recognizing birds in their natural habitats.
  • Hunting: While you are out hunting on lush green meadows or dense forests, the diameter of the objective lens (42 mm or more) and a wide field of view to ensure that you never miss out on any crucial detail are factors to keep into consideration and that’s what makes the best binoculars for elk hunting.
  • Astronomy: If you want to go stargazing with your loved one on a starry summer night or want to have a good look at the celestial objects, then astronomy binoculars can serve that purpose well. They have a massive magnification (10X or higher) and a larger objective lens (42 mm or higher).
  • Traveling: Compact, space-friendly and lightweight binoculars are something to opt for while out traveling, camping, or hiking. Thus, you have to settle for a small-sized aperture.
  • Watching Sports: Choosing the right type of best binoculars for sports will transform your sporting experience from dull and drab to excellent quality one, whether it be a football match or ice hockey. A wider field of view is something you should aim for in this case.
  • Whale Watching: Weather-resistance, especially waterproofing, is something to consider while looking for the best binoculars for whale watching and other uses when on water.
What Do The Numbers on Binoculars Mean

What Do The Numbers on Binoculars Mean?

So after having a bird’s eye view of the binoculars and their uses, now it is time to dig deep to find out what do the numbers on binoculars mean. By doing this the next time, you would be much more confident and know what you are getting into while buying a pair of binoculars.

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So let’s begin!


The first number you see on any pair of binoculars, for instance, 10 in the case of 10X42, represents the number of times the optical gadget enlarges your desired sight of view. Hence, the magnification of the binoculars is the degree to which a pair of binoculars bring the world closer to your eyes.

Most specialists agree that the optimum magnification for a pair of binoculars lies somewhere between 7X and 10X, depending on the purpose for which you want to use particular binoculars. For instance, for marine use, a pair of binoculars with a magnification of 7X would work nice. Still, in the case of astronomy binoculars, you need to have a magnification of 10X or higher.

But one thing to keep in mind is that the higher the magnification is, the narrower the field of view is. Thus with an optical gadget providing a massive magnification, there are chances that you would miss the bigger picture of the view; therefore, the rule of “the bigger, the better” doesn’t really work in the case of magnification.

Some models in the market also offer varying magnification termed as zoom binoculars that give you the control to zoom in to some specific detail or zoom out to get the overall bigger picture of the view. For example, in 10-22×50 binoculars, the unit offers a variable magnification with 10X as the lowest and 22X as the highest limit. Such binoculars especially come in handy in the case of hunters.

Another vital thing to consider is that the usage of a pair of binoculars providing a magnification of more than 10X often comes with the problem of the image’s shakiness. The use of a tripod is recommended to resolve this issue.

What Do The Numbers on Binoculars Mean

Objective Lens

Now effective lens diameter or objective lens diameter is the second number written on the binoculars, like 42 in the case of 10X42 binoculars. It shows the size of the aperture, which controls the amount of light transmitted; thus, a hefty objective lens displays excellent light-gathering ability. Hence the larger the lens diameter is, the more is the amount of light it transmits, and the brighter is the view you would get. 

Moreover, the size of the objective lens also directly impacts the color reproduction. Let’s be honest; every one of us wants a pair of binoculars that provide bright and sharp imaging from dusk till dawn. You should consider the option that offers you a large, at least 42 or 50 mm of objective lens diameter that can ensure a quality view with true-to-life color from sunrise to sundown.

An important thing to consider is that the size of the objective lens directly impacts the size and the weight of the binoculars. Therefore a pair of binoculars equipped with a large objective lens weighs more than its counterparts.

Field of View

Pondering about what do the numbers with degree signs or written with feet/yards on binoculars mean? They account for the field of view of the optical gadget.

Field of view accounts for the total area or the horizontal width of the view you can grasp with a pair of binoculars without the movement of your head. In case of the field of view, the wider, the better rule, sets in as with a wider field of view you would be able to spot the thing you want to focus on instantly, and it would ensure that you won’t miss out on any crucial or once in a lifetime moment. A field of view wider than 315 feet at 1000 yards (105m at 1,000 meters / 6.0°) would serve its purpose justly.

You can better understand what a field of view of 315 feet at 1000 yards looks like by imagining that two objects are placed 315 feet apart from each other, and you are standing 1000 yards away from both of them. In this case, the whole area between these two objects is the field of view that you can see with the binoculars in one go without moving your head.

If the field of view offered by the binoculars is small, then it can’t provide you with a bigger picture in a small frame, and you have to struggle to keep everything in view. In order to catch the very essence of the view, a balance between the field of view and the magnification should be considered.

What are The Crucial Numbers Apart From The Ones Written on Binoculars’ Bodies?

To completely get the essence of exactly “what do the numbers on binoculars mean?” you should understand that some numbers are not written on the body of the binoculars. You should still know about them to land on your perfect pair of binoculars because they significantly impact the binoculars’ functionality.

Exit Pupil

The exit pupil is the breadth of the stream of light leaving the eyepiece of the binoculars. It is a virtual aperture in an optical gadget and a small bright circle that can be seen in the eyepiece’s middle. It is calculated by dividing the objective lens’s diameter by the magnification it provides and is usually expressed in millimeters. For example, in the case of 10X50 binoculars, the exit pupil will be 50/10 = 5 mm.

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The exit pupil number is something you should also consider because it tells how much brighter your image would seem to be in low light conditions. The higher the exit pupil number is, the brighter will be the image you will get. So the best low light binoculars are the ones offering an exit pupil of 5 mm or higher. We can conclude it this way that for daytime view, an exit pupil of 5 mm (or in some cases even smaller but higher than 2 mm) would serve right as the exterior light is enough. At night an exit pupil of 7mm is usually recommended to get a clear and crisp view.

Eye Relief

Eye relief is the optimum distance between your eyes and the eyepiece of the binoculars. It is the distance from the eyepiece lens’s outer surface to where the exit pupil is formed. The viewer would be able to grasp the whole essence of the picture only if his eye is within this distance. If the eye is closer to the eyepiece than this ideal distance, you won’t be able to get an edge-to-edge clarity. If this distance is farther than the ideal eye relief distance, you won’t get the bigger picture.

It does not matter whether you wear the eyeglasses or not; you can still use the binoculars quite well and have a great view of your target with a unit offering generous eye relief. The minimum bar of eye relief in binoculars is set at 16mm, ensuring an encouraging view. The ideal eye relief offered by the binoculars for people with glasses lies somewhere in-between 17 to 20 mm to ensure that they can have the full view without any restriction.

Close Focus

Close focus is the closest distance (between the desired object of view and the image sensor) that a pair of binoculars can focus on efficiently. Thus, the shorter the close focus will be, the more you can focus on the details to which the naked eye can’t entirely do justice. Close focus plays the most crucial role if you want to look at something really close, like a butterfly or an insect on the leaf of a flower or blade of grass.

Not only that, but it can also magically transform your birding experience as you will be able to get a detailed close view of a hummingbird with a pair of binoculars having a short close focus or minimum focus distance.

What are The Additional Features to Consider?

Apart from the numbers that add to the binoculars’ functional specs, some features add to the binoculars’ structural quality and functional quality and promise excellent performance.

Weight And Size

Size and weight of a binocular play a significant role as there is a lot of demand for compact and lightweight options that can easily be used when you are out camping, hiking, biking, or hunting. Because frankly speaking, who wants to carry those extra pesky pounds with oneself when you are out on a trip? No one, Right? And that’s what points in the direction of the need for light-weight, compact binoculars so that you will be more poised moving it from one place to another.

But on the downside, the small-sized binoculars have a low field of view and less brightness than the larger ones as they usually come equipped with a smaller objective lens. Thus a smaller objective lens means less bright view. Therefore you should select the right size of the binoculars to suit your purpose of viewing.

  • Compact Binoculars: These binoculars usually have an effective lens diameter of less than 30 mm (25 or 28 mm), are space friendly, and work well in good lighting conditions. They can serve the purpose decently while you are birdwatching, hiking, or trekking.
  • Mid-Size Binoculars: These binoculars usually have their objective lens diameter between 30 to 40 mm. So if you switch places more often when hunting or birding, exhaustion may creep in pretty fast; thus, mid-size binoculars can serve the purpose here. But on the downside, these binoculars are not suitable for low light conditions.
  • Full-Size Binoculars: These binoculars have an objective lens of 40 mm or larger that makes them an excellent choice in a multitude of lighting conditions. They can even be used to stargaze or watch other celestial objects like the moon. They are heavy binoculars, and you need to have a tripod to mount them on if you are planning to use them for an extended time.
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Durability and Waterproofing

What’s the point of buying a pair of binoculars that can’t even survive a few falls or can’t handle a drizzle or rain? So durability is a feature that you should not neglect while buying a pair of binoculars. Most binoculars now offer a rugged rubber armoring that adds an extra layer of protection for the binoculars and gives them a firm grip. Apart from that, when you are out on the field to watch your favorite sporting event or your favorite artist’s concert, you can’t always predict the weather.

So you as well as your optical gadget should always be ready for any capricious change in weather. So what you should do is look at the durability of the model because, frankly speaking, Guys! You are spending your hard-earned money on buying the optical device. Hence your binoculars should provide you with features like waterproofing, fog-resistance, scratch-resistance, dust proofing, etc. so that you won’t have to worry about the view’s haziness in a humid environment or the accidental water splashing on your pair of binoculars.


Hence the roller coaster ride that we started to comprehend that what do the numbers on binoculars mean has come to an end. To sum up the whole idea, you should always remember that the numbers on the binoculars reveal the overall potential of the item.

Choosing the right pair of binoculars is not an easy task, especially when the market is swarming with options of different specs and sizes. We have tried our best to simplify the whole thing for you by talking about all the numbers and features you should look for before making a purchase. After reading this in-depth analysis, we hope that you can fully understand the concept that what do the numbers on binoculars mean.

Have a nice day!



Q. What is a Field Of View?

A wider field of view in binoculars, exceeding 315 feet at 1000 yards, enhances the ability to instantly spot and capture crucial moments without the need to move your head. It can be visualized as the entire area between two objects placed 315 feet apart, observed from a distance of 1000 yards, providing a comprehensive view in one glance.

Q. Which is The Best Magnification For Binoculars?

Ans: Magnification tells us about the degree to which a particular image is enlarged compared to the normal one, As magnification has an inverse relation with both field of view and eye relief, therefore it ain’t always that higher magnification will always be better. Therefore, a magnification of 7X to 10X could serve the purpose well.

a magnification of 7X to 8X will be enough to please a sports fan or a bird watcher while big game hunters would need a pair of binoculars offering a high magnification of about 10X to satisfy their needs for long-distance viewing.

Q. What Does The Number 20 X 50 on The Binoculars Mean?

Ans: The first number you see on the pair of binoculars, 20 in the case of 20 X 50, represents the magnification which means that the pair of binoculars enlarges your desired sight of view  20 times. The second number represents the diameter of the objective lens which is 50 mm in this case. Last but not least, the exit pupil is 50/20 = 2.5 mm.

Q. What is The Highest Magnification of The Binoculars?

Ans: To this date, 160 X is one of the highest magnification that a pair of binoculars offers which means that the particular pair of binoculars can bring the distant scenery 160 times closer to your eye.

Q. What is The Close Focus of The Binoculars?

Ans: Close focus is the closest distance (between the desired object of view and the image sensor) that a pair of binoculars can focus on efficiently. Thus, the shorter the close focus will be, the more you can focus on the details to which the naked eye can’t entirely do justice.

Q. What are The Best Numbers For Binoculars?

The best numbers for binoculars are typically represented by two values, such as 8×42 or 10×50. The first number indicates magnification (8x or 10x), and the second represents the objective lens diameter in millimeters (42mm or 50mm), influencing brightness and field of view. Choose based on your specific needs, balancing magnification and light-gathering capabilities.

Q. What To Look For When Buying Binoculars?

When buying binoculars, consider factors like magnification power, lens diameter, and field of view. Opt for a reputable brand with good optical coatings for better image clarity and durability. Additionally, ensure the binoculars are comfortable to hold and easy to adjust for individual preferences.

Q. What is The Most Popular Binocular Size?

The 8×42 binocular size is widely considered the most popular, striking a balance between magnification and light-gathering capability for versatile use in various activities like bird watching and outdoor exploration.

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