There’s a really useful diagram on Wikipedia that shows the relatives sizes of different digital camera sensors. But it doesn’t include medium format film – so I made my own version.
|Format||Typical use||Size||Area||Crop factor|
|APS-C||Most consumer DSLRs and APS film cameras||~22x15mm||330mm²||1.5-16×|
|35mm||Professional full frame DSLRs and all 35mm film cameras||36×24mm||864mm²||1.0×|
|6×4.5||Medium format cameras e.g. Mamiya M645||60×45mm||2700mm²||0.58×|
|6×7||Medium format cameras e.g. Mamiya RB67 & RZ67, Pentax 67||70×60mm||4200mm²||0.47×|
|6×9||Horseman 980, many box & folding cameras e.g. Kodak Brownie||90×60mm||5400mm²||0.40×|
The crop factor is related to the field of view. To achieve the same angle of view as a 35mm camera, an APS-C sensor needs a shorter focal length while a 6×7 sensor needs a longer length. For more details, have a look at my article “focal length on different formats“.