35mm - 36mm x 24mm image frame - (35mm refers to the diagonal) the most popular format of the 20th century, traditionally used in amateur photography, sports and journalism where speed, efficency and portability are important
645 - the smallest of the medium formats, still 2.6 times bigger than 35mm. 16 shots per roll of 120 film.
6x6 - popular square format used by Holgas and Hasselblads. 12 shots per roll of 120 film.
6x7 - popular medium format due to its agreeable aspect ratio. 10 shots per roll of 120 film.
6x9 - same proportions as 35mm film, just a 5.2x larger negative! 8 shots per roll of 120 film.
612 - large 2x1 panoramic format, almost the same width as 5x4 sheet film. 6 shots per roll of 120 film.
5x4” - large format photography, comes in a box of sheets that you manually load into film holders.
not shown:
6x8 - rare medium format. Some Japan-only Fuji rangefinders.
610 - rare panoramic format. Plaubel Veriwide.
617 - extra wide panoramic format on 120 film, requires lenses with large image circles. 4 shots per roll of 120 film.
624 - insane super panoramic medium format, used by rare, specialised cameras. 3 shots per roll of 120 film.