Here the Film Formats, which were used by Photo-Reichmann:
Small Picture (Kleinbild, KB) [35mm] :
Dimensions:
24 x 36 mm
Square Measure: 864 mm2
Remarks:
Most popular Filmformat.
Advantages: Cheap in purchase and reproduction.
Disadvantages: Less good to enlarge.
Supply of the 135er* Film´s assembled at 12, 24 or 36 Exposures, i rather prefer the 36er Filmrolls.
Small Mediumformat (kleines Mittelformat) 6 x 4,5:
Dimensions:
60 x 45 mm
Square Measure:
2700 mm2
Remarks:
3,125 times bigger than 35mm
Advantages: Better: enlargement, sharpness, color saturation.
Disadvantages: Expensive: in purchase, developement and reproduction (Don´t even Think about the Camera and the lenses...)
Supply of the Mediumformat Rollfilm as *120er Film: 15 Exposures at 6 x 4,5 cm.
The Rollfilm is available as *220er Film too, with the need to buy another new special Cassette.
Big Mediumformat (Königsformat) [Kingformat] 6 x 7:
Dimensions:
60 x 70 mm
Square Measure:
4200 mm2
Remarks:
4,861 times as 35mm, THE classic Filmformat,
without the need to cut the Classic Photopaper ( 8 x 10" ).
Advantages: (even more) Better: enlargement, sharpness, colorsaturation.
Disadvantages:
(even more) Expensive: in purchase, developement and reproduction
(The Cameras and lenses are [much] more Expensive than the 645...)
Supply of the Medium Format Rollfilm as *120er Film: 10 Exposures at 6 x 7 cm.
The Rollfilm is supplied as a *220er too, with the need to buy another new special Cassete...
Definitions:
*120er Film, describes a Rollfilm with a width of 6 cm and a length of 12 Exposures at 6 x 6cm.
*220er Film, describes a Rollfilm with a width of 6 cm and a length of 24 Exposures at 6 x 6cm.
*135er Film, describes a 35mm Film with the diameters 24
x 36 mm with 12, 24 or 36 Exposures,
Labelled as 135-12, 135-24, 135-36.
Direct compare of the Formates:
KB 
6 x 4,5 
6 x 7