Yesterday I asked if anyone had any info on why medium format film is commonly called ‘120’. I knew that the notion that it had something to do with 120 millimeters was simply not true, but I couldn’t seem to find a source for why it had taken on the moniker of ‘120’ in the first place. A few kind folks did some better googling than I did and found the definitive answer. Here it is, in a nutshell:

According to this article…

[Kodak] … decided that … roll films … would be numbered in the order of introduction, starting with … number 101.

This system was gradually phased in as new film boxes and camera instruction manuals were printed … [and] numbers 101 through 129 were used.

I also liked this passionate plea:

Please, please, please, don’t mistakenly call this size “120mm.” Even B&H’s online store has been known to get this wrong. The film is actually about 63mm wide, and the 120 is just an arbitrary number from the dim mists of Kodak history.

Now we all know!