How To Measure Camera Lens Size

There are various reasons for knowing how to measure camera lens size.  But the main reason for most is for the use of threaded filters.

This article is focused on those who want to determine their camera lens size/diameter. If you would rather know how to measure and use your focal length (mm of lens) - then head to my other article here.

This article will discuss how to measure camera lens size and the benefits you will receive for knowing that information.  

By the end of this article, you’ll be able to move forward and use this information to your advantage!

Without further ado, let's get going!

How To Measure Camera Lens Size

Diameter of your lens

How To Measure Camera Lens Size

When you first purchase a new lens, your creative side of your brain is thriving.  You’re imaging what kind of shots you’re able to achieve and how much better they may be over your current work.  This is something that everyone who uses a camera experiences.  

What most people who are starting out don’t think about (and even those who have been using cameras for a while), is the lens diameter.

While it isn’t a big deal for most lenses, there are few things that are affected by the diameter of your lens.  The main aspects include:

  • Size and price of filters
  • The ability to use filters

The diameter of your lens determines the size of the threaded filter 

That’s right.  The diameter of your lens determines the size of the threaded filter you’re able to put on your lens. Generally speaking, the larger the diameter the more expensive the filter will be.  If you find yourself owning (or wanting) to own a lens with a 77mm+ diameter (or filter thread), expect to pay more for a filter than someone with a 67mm or lower.

There are lenses on the market that don’t allow threaded filters on their lenses.  This is because of the curvature of the lens.  Many wide and ultra-wide lenses on the market don’t physically allow them.  The lens itself creates a curve or “bubble” at the end of the lens.  A normal filter would actually hit the glass.

This is something you’ll need to find out before you purchase the lens.  You either have to be ok with it (and not use filters), or purchase a much more expensive mountable filter.

Let’s discuss how you measure your camera lens size!

The numbers on your lens

How To Measure Camera Lens Size

When you scan over your lens, you may notice there are a fair bit of  numbers located all over it.  You have focal length, f stop (sometimes a range), minimum focal distance, and so on.

What you’ll want to focus on is ⍉.  This is the symbol for diameter.  The number that follows is the diameter of your lens.  An example of this would be ⍉77.  This would mean that your lens size (or diameter) is 77mm.

You don’t have to physically measure the lens.  Most lenses on the market have the information right on the lens itself.  If you find yourself using an older lens where the markings have rubbed off (or your lens doesn’t show it) - you can take a fine ruler that has marks for mm.  You would then count them.  This is very rare though.

If you can’t find the diameter of your lens on the lens itself - you could also look it up online.  Most lens information is all over the internet (for nearly every lens on the planet).

What you can do with this information

Like stated at the beginning of this article - there’s only one purpose for knowing the diameter of your lens.  That’s to use threaded filters on the end of your lens.  You also need this information for lens caps.

While there is only one reason (filters), there are many types of filters that can help you in both photography and videography.  These filters include:

  • Neutral Density (ND)
  • Polarizer
  • Infrared
  • Macro
  • Astrophotography (light pollution)
  • UV
  • Clear (for protection)

… and believe it or not, there are actually more than that.  You should do you research on each of them to see if you can benefit from them.  I have an article on ND filters here, there’s everything you’d need to know about them there!

So that’s it!

Yup, it’s really that simple.  When i first learned this, I couldn’t believe how easy it was to figure it out.  And honestly, as you use lenses over the years to come, you’ll be able to pick up a lens and quickly tell its diameter without having to look at the markings.  

I hope I answered your question and more!  You should be able to take this information and purchase a few accessories that could help you with your photos and/or video!

Be sure to checkout JnRPhotoVideo.  My wife and I run a photo and video service here in San Diego!  You can view some of our work there!  Be sure to give it a look!

As always, thank you all so much for reading!  Until next time, keep shooting and creating!


I have been taking photos and film since I was a child. Now that I'm in my mid 30's, I want to share with the world what I have learned over the years. I attempt to live every day to the fullest and share that with you through my blog. I am an electrician by trade and photo and video lie within the "hobby" aspect of my life at the moment. It's what I'm truly passionate about.
Back To Top