There Is No Such Thing As 120mm Film!

Right. There’s no such thing as “120mm” film. The format is called just “120”!

I’m writing this post as part of a concerted effort to correct this bizarre misconception that seems to have taken over the internet. It’s most prevalent on Instagram where there are whole accounts dedicated to “120mm” and the hashtags #120mm and #120mmfilm have been used hundreds of thousands of times.

What’s worse are the online shops that have started calling the film 120mm in their shop listings – either through gross ignorance, or some attempt to optimise their websites for people searching the internet for this non-existent film format.

Let me repeat. There is no such thing as “120mm” film – not by designation at least – it is simply called “120”.

120 – the Kodak nomenclature

Ok, so why is it called “120” then? It’s quite simple – that’s what Kodak called it! Back in the early days of film, there were lots of different formats for lots of different cameras. As far as I can work out, in a bid to make things easier to understand, in the very early 20th century, Kodak started naming their films with numbers. 2 1/4” roll film was given the name “120”.

If you’re interested in reading more, there is a very informative Wikipedia article that details all the information here

Where do the misconceptions come from?

I have been baffled by this addition of “mm” to the 120 designation for a while, and have long wondered where it came from. I’ve long guessed that it originated from someone – or one might assume a lot of people – taking the “mm” off the end of “35mm” and adding it to 120. An easy mistake to make, perhaps, though it doesn’t make much sense in practice.

35mm film – which Kodak named “135” – is in fact 35mm wide. 120 film is about 61mm wide. 135 film has sprocket holes which take up the edge, so the part of the film that is exposed is actually on 24mm wide. About 56mm of 120 film is exposed to the light.

With both films, the other dimension of the exposure varies depending on the camera. 135 cameras range from 24x18mm to 24x65mm with 24x36mm being by far the most common format.

120 (medium format) cameras are a little different as there are lots of different formats with none of them being the “standard” format. In more modern times, the various 120 or “medium formats” are based on rounded numbers.

As an example, there are 645 cameras – the name 645 comes from a rounded size of exposure they take. They take 120 film, and the actual exposed part of the film is about 56mm x 41.5mm, but to keep things simple those millimetre measurements are rounded-up to 6cm x 4.5cm which in turn gives the 645 naming convention.

The same goes for 66, 67, 68, 69, 612 and 617 cameras. A 69 camera takes photos that are a little bit smaller than 6x9cm.

A 67 frame – 120 film is 61mm wide, the exposed frame is ~56mm x ~69mm

As you can see, the only medium format film format that has anything to do with 120mm is 612 – a format that is slightly less than 120mm on the long edge. But, this is far from the standard – the wider 612 and 617 formats are a lot less common than 645-69 formats. As such, there is no reason that 120 film would take its name from that wider format.

I also read the other day that some people think that 120 comes from the fact that 120 is 60 x 2 – i.e. the 66 format is where the name originated. With the rounding of numbers, I suppose it’s reasonably logical that this might be the case, but if you look at the chart on Wikipedia, there is no evidence of this system anywhere else, and in fact, it would appear it was just the 20th format to be given a name under the Kodak system of nomenclature. Additionally, as stated, 66 is no more standard than any other format.

So yeah, to repeat myself again, the format is called 120, and not 120mm as the latter doesn’t make much sense at all.

Does it really matter?

Of course, in reality, it doesn’t really matter… When people say 120mm, those of us who know they are misnaming it, also know they mean 120.

It’s just, well, why add the “mm” to the end? Why make it more confusing? Why sully the Kodak nomenclature that’s been around for 118 years? Calling is 120mm isn’t really hurting anyone, it’s just a bit stupid!

So what can we do to correct it?

If you find yourself rolling your eyes at all this 120mm nonsense, why not join me and EMULSIVE in trying to correct it? Here are some resources for you to use:

A website we’ve made –

This post

A rant on EMULSIVE –

The film format article on Wikipedia –

Twitter – @120NOT120MM

Instagram – @120_not_120mm

Facebook group – 120not120mm

Wherever you see this heinous misdemeanour, why not link to one of the above – you can even use the hashtag #120not120mm to help hammer the message home!

All of this will start spreading the word to all these people and accounts who are habitually compounding this nonsense!

Is it too late, has social media spread this post-truth nonsense too far and wide? Are there more important issues in the world that you could spend your time and efforts on? Probably, but I just can’t help facepalming every time I see #120mmfilm, and frankly, my forehead is starting to hurt…

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37 thoughts on “There Is No Such Thing As 120mm Film!”

      1. Good luck, Hamish. Once the internet stupid picks up on something, it is almost impossible to correct an error. But I can understand how novice users must have assumed that mm followed 120 similar to mm following 35. Another common contemporary error is novice users claiming they need a circular polarizer. Many could get by with a linear polarizer, but the term “circular” always creeps in.

        1. Actually, a linear polarizer can mess up auto-focus and TTL metering as the linearly polarized beam will not be transmitted / reflected in the expected proportions by the beam splitter, hence the addition of the quarter wave plate after the polarized in modern polarizers.

          BTW a quick way to tell which you have is to look at your monitor through it. A linear polarizer will show an extinction from both sides, while a circular one will only show a variation if the light is coming in from the front.

  1. Dominique Pierre-Nina

    HI Hamish, mate the whole photography community is in disarray at the moment.
    1: Every one is a ” Photographer” there are so many imagers out that 99.9% of it is irrelevant , nothing is inspiring, Instagram has lost it’s appeal, it’s all about me, me, me.
    2: Second, everything is about the camera ( What is it like to shoot with this or that) nothing about photography to the photograph. A camera will not make you a better photographer period.
    3: The film issue again every one is all about what type of film they using without any understanding of it, eg calling 120 (120mm) etc.
    Its time to seperate the chaff from the wheat I say.

  2. Hopefully, if enough people complain on enough sites, then this falsehood may be rectified. But I am enough of a pessimist on this one to think that all those who’ve already picked up this error won’t be reading these sort of blogs. Sad.

    The one big falsehood that really gets my goat, is that tele lenses compress the subject. In reality, they don’t, and it can easily be explained why, but don’t get me going on this subject!

    I came across one site where the owner claimed that all the DoF scales on lenses were wrong. So Leitz, Zeiss, Schneider, Canon, Nikon, Minolta, olympus, et al didn’t know what they were doing? Only he knew better.

    Hamish, IMO, the 645 format is more than rounding up the actual size of the negative, although the practice does tidy up format sizes that 120 film can be used for when using metric. Taking your measurements produces an almost perfect 4/3rds format and which, funnily enough, is exactly what 6×4,5 is. Interestingly, the old English naming of 2 1/4 square for 12 on is much closer to the real thing than 6×6, i.e. 56.3mm

  3. Well said that man!
    A brave attempt to stem the rising tide of photographic ignorance!

    Reward yourself with a camera purchase!

  4. LOL, I been looking everywhere for some 620mm film for my bakelite-bodied Kodak Brownie. Maybe Japan Film Finder can find me some. Bellamy?

  5. I wish you the best of luck with this campaign! Can we also go back to calling so-call ‘full frame’ the Miniature Format, as it was known in my youth when 120 and 620 film were the standard. By the way I’m not sure that 120 was ever known as Medium Format back in the day :-).

    1. Richard, how dare you! The “photographers” on the infamous Dpreview will wet their trousers in orgasmic fury and outrage if you tell them that “full frame” is really just a miniature format. 120 film, you mean medium format? That is for rich dentists, poseurs, and pixel-peepers. Everyone serious or “professional” (i.e., the Dpreview jokers) uses full frame.

  6. Thank you SO MUCH Hamish – this is one of those things that really get under my skin!
    One of the worst offenders is a long-established camera dealer – ‘Mr.Cad’ (latterly of Croydon – now in Central London)
    Every 120 film listed on the site is described as ‘120mm’
    I’m not a social media user, but I have emailed the link your new website to the company.
    Here’s hoping…

  7. 120 film is closer to 70mm than any other metric dimension. Witness the number of pro cameras that offered 70mm backs to interchange with 120 and 220 … back in the day.

  8. That is a big pet peeve of mine, especially when I start hearing people’s explanations…

    Like the camera is 6×6/6×7/6×9 – how did you get 120mm out of that?

  9. I’m glad I’m not the only one who finds this irritating. The other thing that gets up my nose is the spelling of lens as lense. Is there such a thing?

  10. Of course you are right Hamish. My first camera; for my 10th birthday in 1948 was a Kodak Brownie Model E which I still have. It takes 620 film. That’s not available nowadays but I can buy a roll of 120 film and then in a darkroom I can carefully wind all the 120 film onto spare spool. Then I wind it back onto a 620 spool which has a narrower centre than the 120 spool. Then I can take photos on my old Brownie Model E. So 120 film and 620 film is exactly the same size but the spool size of the 620 film is thinner to fit in the Brownie camera.

    It is necessary to double wind the film as it is stuck to the backing paper with tape only at the leading end of the roll. I still have some 620 spools which I retain.

    Same film, different spools, and different numbers assigned by Kodak.

    The negative size in this case is nominally 2,1/4” X 3,1/4” or 6 X 9 cm.

    That old Brownie camera can take very good photos in good light but it’s a good idea to cover the red film counter window in the back, with some black tape and only lift the tape to wind on in the shade of your body. Early orthochchromatic films were not very sensitive to red light, but more modern panchromatic, and of course colour films, could be partly fogged through an uncovered counter window.

  11. You know you’re banging your head against a wall don’t you? It’s Instagram – the idiocracy of the photo world. Leave the poor buggers alone in their blissful ignorance. It is after all what they crave, why they are on it.

    Did you know 127 film is better than 120mm? It’s like 7 better.


    Good luck and all the best.

  12. Good thing 220 film is no longer readily available eh. Film and sensor formats have always been a smorgasbord. Half plate, whole plate, 8×10, 4×5 etc. I noticed that in the UK its 5×4. Which is correct, and who really cares. 35mm and half frame format, and then micro 4 thirds, APS and so called full frame…I get it I totally get it that its maddening. I have similar reactions to the spelling of the English language. Color vs Colour, Centre vs Centre. Cheque vs Check….and on and on it goes. Now that Ive had my mini rant, I feel better, I hope you do too Hamish. Thanks for sharing and BTW I’m with you on this one.

  13. We always called the film ‘medium format or 120 film.’ While we’re on the subject of ranting…Hasselblad camera were called ‘Blads by pros…Not Hassys or Hassies…that was an amateur term.

  14. This is enlightening, Hamish, I was also questioning the same when I started trying Mamiya RB67, where different film format is used. Since I was still familiarizing myself with this new film format, I was wondering why was it called 120mm, as the width is not at all 120mm.

  15. Another bugbear is saying that 120 roll films have 12 exposures.

    It took me several attempts to explain to a user on one of the forums that I frequent, that the division of roll film into frames is purely a function of the camera and that their 6×9 camera would have a red window that sees the right set of number for the 8 exposures that it will take, so no need to skip 4 at the start or the end.

    P.S. I have also seen 127 film called 127mm!

  16. Hamish, love your site. It’s one of only 3 blogs that I visit daily. But I’ve got to say, to me at least, this is a total non-issue. As long as people are talking about film and cameras, I don’t care if they’re talking about spools, cassettes, 35, 135, 120, 120mm,220mm,, long-spoolie-holey-film or tall-standy-uppy-film. We all learn as we go. I try help people right when I hear they have something wrong, but it doesn’t bug me in the least that they got it wrong in the first place.

  17. Bravo, Hamish! This one has been bugging me too since I became an occasional 120 user, and it’s comforting that I’m not alone.

    One more reason why the error does matter: the mythical 120mm is close to five inches, and 5×4 belongs to a very different school of film photography. (‘127mm’ would be even closer, of course — but fortunately there’s not much 127 film left to confuse people further.)

  18. Pingback: Film Formats – WTS? (What the Size) – Alex Luyckx | Blog

  19. Andrea Bevacqua

    I find this article informative. It does not change the life but I think it is important to speak correctly (…and if I say it… 🙂 ). Is just a matter of being correct.

    Thanks Hamish

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