What do binocular numbers mean? | Best Binocular Reviews (2023)

The BBR Video above answers the question: What do the numbers mean on a binocular and is part of my Binoculars 101 series on What To Look For When Buying Binoculars.

The article below was written by Derek Sergeant and takes the perspective of a newcomer learning about the importance and meaning of the numbers on a binocular:

So what do the numbers on binoculars mean?
I asked this question in a hurry. We were at the airport waiting to fly to Peru, on a once in a lifetime trip was planned to the last detail.

I had forgotten to sort out binoculars for our stay on an oxbow lake in the Amazon. With so much variety I had to understand what do binocular numbers mean?

In this article I am going to explain about the two numbers often found printed on the body of a binocular and why understanding binocular numbers is important.

The binoculars in front of me are and 8x42. Searching for the extremes in front of me, I found 6x21 and 25x150 and wondered what do they mean and why are these numbers important?

Binocular Magnification

Of the two numbers in my “8x42” example, the first number is its magnification.

(Video) Binoculars 101: What do the numbers on binoculars mean?

Binocular magnification is sometimes referred to as power, I will just use the term magnification. You will notice the “x” alongside the “8” in my example, this belongs with the number. Meaning “8x” or eight times magnification.

Why Is Binocular Magnification Important?
The main purpose of binoculars is to allow you to see a distance object more clearly by making them look larger as if you were seeing them from much closer. My “8x” binocular makes the object I am looking at appear eight times larger than it would if I look at it with just my eyes (unaided).

Binoculars with 8x40, 8x42, 8x70, 8x32, or even 8x21 all offer the same magnification. They will all magnify the image by eight times. Likewise, 10x42 will magnify ten times, 12x50 will magnify twelve times.

How about 30-160x70? This example is taken from the Sunagor 30-160x70 BCF Mega Zoom Binoculars. It has a range of magnification (sometimes referred to as zoom binoculars) 30-160x, and thus the power can be adjusted anywhere between 30 times and 160 times.

Bigger is Not Always Better!
This is a common newbie mistake and it is important to realize that high magnifications will not suit all intended uses.

Indeed, for most uses, 8x or 10x is ideal and going any higher has many detrimental effects that will seriously hamper your viewing experience.

For more about the competing factors for choosing magnification are in this guide to .

Objective lens size

Of the two numbers on my “8x42”, the second indicates the diameter of the main objective lenses, in millimeters.

Using the same examples, an 8x42 binocular has 42mm diameter objective lenses.

(Video) Everything You Need To Know About Binoculars

Whereas 8x21 has 21mm objective lenses, although with the same 8x magnification.

Comparing 6x21, 8x21, 8x40, and 10x42. These have objective lenses with diameters of 21mm, 21mm, 40mm, 42mm.

Why is this Important?
The surface area of the objective lens captures light from the scene and transmits it to the ocular lens (which then transmits that light to your eye).

A larger objective lens captures more light and so the image seen is potentially brighter than on a smaller one.

In low light conditions the more light that can be captured and transmitted to the eye the better.

A 42mm objective lens has four times the surface area of a 21mm lens, and so has the ability to captures four times more light (area = pi x radius squared).

25x150 binoculars capture over twelve times more light than 10x42.

Large 80mm Binoculars For Astronomy Need A Tripod

(Video) how to choose binoculars | best binoculars on a BUDGET

Getting The Balance Right
If larger lenses lead to better quality, brighter images, why not just get the biggest lenses you can. Well, the downside to this is obviously that it makes the instrument bigger and heavier and thus less convenient to carry about.

Where light gathering and low light performance is critical, like astronomy, for example, binoculars can have very large 100mm lenses or even more in some cases.

However, this means that they are now so large that they have to be attached to a tripod to use them which is certainly not ideal if you need easy to carry binoculars for birdwatching when out in the field.

You can also have too much of a good thing with the binoculars supplying your eyes with more light than they need.

This relates to the size of the pupils in your eyes and how wide they are dilated depending on the available light and is in relation to the size of the shaft of light exiting the eyepieces.

This can get very technical and if you are interested, read BBR’s complete guide to the exit pupil.

42mm Binoculars
But for now, just know that a 42mm binocular, like an 8x42 or 10x42, is considered to be a standard “full sized” instrument and a good compromise between size and light gathering ability.

Mid Sized Binoculars
Instruments with lenses around 30mm to 32mm are considered a mid-sized instrument slightly favor portability over the light gathering ability. So whilst they are perfectly fine for use during the day, they are not the ideal choice in very low light.

What do binocular numbers mean? | Best Binocular Reviews (5)

Binoculars with lenses between 18mm and 28mm are usually referred to as compact binoculars.

(Video) 8x42 vs 10x42 Binoculars - Which is Best?

Here it is all about ease of carrying and portability. Thes binoculars work best in good light and are ideal for uses like hiking, camping, taking to outdoor sporting events, walking safaris, etc.
For more take a look at this article on Which Compact Binocular is Best.

Do these numbers tell the whole story?

So we have established that the binocular numbers provide the magnification and the size of the objective lenses on a bino. The surface area of the objective lenses can be calculated, which determines how much light is captured by those particular objective lenses.

The two measures, magnification, and size of objective lenses relate to the field of view. Field of view is how wide an area is encompassed in the image seen through the binocular.

As the size of the objective lens increases, so does the field of view. As the magnification on a binocular increases the field of view decreases. So almost every 8x42 has a wider field of view than a 10x42. Just remember, other factors also affect the field of view, so two 10x42 from different manufacturers may have a different field of view.

Also: The numbers do not indicate how much of the light captured is actually transmitted to the eye, as the quality of the materials used in the lenses and other components on the light path determines how much light is lost (not transmitted).

They also do not indicate the weight of binoculars, as more powerful magnification and larger objective lenses will increase the overall weight. This may determine whether the binoculars can be used handheld or using a tripod (or with a monopod).

There are many other factors that influence the suitability of binoculars for a particular intended use. How big is the eye relief? How large is the subject being observed? How far away will you be from the subject? What is the minimum focus distance?


What do the numbers on binoculars mean?
I hope you have found this article formative and that it has helped to
explain binocular numbers for you:

To recap:

(Video) Cheap vs Expensive Binoculars - What's the Difference?

  • The first number (including the X) is the power (magnification).
  • The second number (immediately following the X) is the size of the objective lenses.

Together these numbers inform you how much larger an object will appear through the binoculars, and how bright the image is seen will appear relative to the amount of light available.

Whilst the binocular numbers do not answer all the questions about a particular pair of binoculars, but it is a good start. For where to go next, take a look below:

Further Reading

  • Next: If you are interested in buying your first binoculars, take a look at our guide: What To Look For When Buying Binoculars

Please contact me if you have any further questions.


What numbers are best in binoculars? ›

Generally, binoculars with a magnification of 6 to 10x are easier to use, but for birdwatching, tracking moving objects, and keeping shaking to a minimum, 8 to 10x magnification is best. For theatergoing, a somewhat lower magnification is easier to use, and portability is an important factor.

Which is better 12x50 or 10x42 binoculars? ›

When comparing the 10x42 UHD to the 12x50 UHD, you get an instant boost of 18.18% in magnification, an increase of 11.42% in weight, a decrease of 18.30% in FOV, but only a 6.45% increase in cost.

Is the higher the number the better the binoculars? ›

First and foremost, the numbers on binoculars are magnification numbers. You'll see two numbers separated by an “x” (10×25, for example); the first number (10x) is the magnification power. The higher this number is, the closer objects will appear.

What does 30x60 mean in binoculars? ›

-They are sold as "30x60" binoculars, which means 30x magnification and 60mm objective lens (although, trying to be clever, the binocular itself says “30*60”). Back to reality, these are 8x21, or 8x magnification, 21mm objective.

How do you tell how strong binoculars are? ›

Model numbers on binoculars essentially tell you their strength (magnification power) and size (objective lens diameter). In 8x42 binoculars, for example, “8” is the magnification power and “42” is the diameter (in millimeters) of the objective lenses (the lenses closest to the object you're viewing).

What are the best binoculars for long distance viewing? ›

If you're looking for a high-quality product, the Nikon 8252 Aculon A211 Zoom Binoculars may be the best all-around binoculars for long distance currently on the market. This pair of binoculars are produced by an extremely reputable and reliable manufacturer.

Which is better 10x50 binoculars vs 10x42 binoculars? ›

If you are looking for a pair of binoculars for general use, then the 10x42 binoculars are a great choice. The 10x50 binoculars are the next step up in terms of quality and versatility. The wider lenses provide a brighter image in comparison and will perform better in low-light conditions.

How far can you see with 12X50 binoculars? ›

This is where we need to talk about compromise between different power binoculars. A typical 10x42 will offer about 330 feet of FOV at 1000 yards, while the average 12x50 is just under 300'; 15x binoculars are generally under 250'.

How far can you see with 10x50 binoculars? ›

10×50 binoculars magnify your normal vision 10 times, so theoretically, you can see for 300 miles.

Are 12X50 binoculars good? ›

The 12X50 binocular “size” is like the prom king of bino configurations. It's ideal for stargazing, long-range shooting, and spotting the prey at a distance. The best 12X50 binoculars are durable, waterproof, and come at a reasonable price.

What are the best night vision binoculars? ›

Best Night Vision Binoculars 2022
  • Dorr Night Owl NOB5X. ...
  • Nightfox Swift. ...
  • Luna Optics LN-G3-B50. ...
  • ATN Binox 4K. ...
  • Zeiss DTI 3/35. ...
  • Nightfox 100V. ...
  • Orion 2x54 Ultra Wide Angle Binoculars. ...
  • Bresser NightVision Binocular 1x.
3 days ago

How far can you see with 12x32 binoculars? ›

1000m field of view: 96m. Exit pupil diameter: 3.8mm.

What are the strongest binoculars? ›

Sunagor's Mega Zoom binoculars are the most powerful in the world, offering magnification up to 160 times. Fantastic if you're interested in wildlife, sailing or plane spotting, they're also powerful enough to explore the night sky.

What strength binoculars do I need to see planets? ›

A pair of 7×35's is about the minimum acceptable for astronomical observing; 7×50's are better… this will give you the same magnification but a wider field of view. These 9×63 binoculars by Celestron give bright images but they are about as heavy as most people can use without a tripod.

What does 20x50 mean in binoculars? ›

Description. These 20x50mm PowerView binoculars feature a massive 20x magnification for long-range viewing, large 50mm objective lenses increase light gathering and viewing comfort.

How far can you see with 12x25 binoculars? ›

Nikon Travelite 12x25 Specs
Angle of View4.2° (Actual)
Field of View220' @ 1000 yd / 73 m @ 1000 m
Minimum Focus Distance13.1' / 4 m
Exit Pupil Diameter2.1 mm
5 more rows

How far can 60x60 binoculars see? ›

60x60 High Power Binoculars,Waterproof/Professional Binoculars,Night Vision, with Suitcase, Maximum Distance of 3000 Meters, Suitable for Outdoor Travel, Boating, Bird Watching, Etc.

Are 10x42 binoculars good? ›

Both outdoor and wildlife lovers find 10x42 binoculars to be an excellent choice when viewing distant objects. While the 10x zoom provides the right amount of magnification, the 42-millimeter diameter of the objective lens ensures brighter images.

How far can you see with 12x32 binoculars? ›

1000m field of view: 96m. Exit pupil diameter: 3.8mm.

How far can you see with 12x25 binoculars? ›

Nikon Travelite 12x25 Specs
Angle of View4.2° (Actual)
Field of View220' @ 1000 yd / 73 m @ 1000 m
Minimum Focus Distance13.1' / 4 m
Exit Pupil Diameter2.1 mm
5 more rows

How far can you see with 10x50 binoculars? ›

10×50 binoculars magnify your normal vision 10 times, so theoretically, you can see for 300 miles.

What are 20x50 binoculars used for? ›

20x50 High Power Military Binoculars, Compact HD Professional/Daily Waterproof Binoculars Telescope for Adults Bird Watching Travel Hunting Football Games Stargazing with Carrying Case and Strap.


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