Small format is the group of film formats that are 35 mm or smaller.
Film gauges referred to as small format include:
35 mm format (Full Frame; FX) 24 mm format (DX) Advanced Photo System (APS) 35 mm film / 135 film / full frame 16 mm film 8 mm film 1-inch digital (CX)
See also Ultra Large Format, 10 inches and more Large format, 4 to 10 inches Medium format, 35 to 130 mm 828 film 126 film 110 film
References