What are the dimensions of 6203?

Short answer (free to quote): 6203 has boundary dimensions 17.0 mm bore × 40.0 mm outside diameter × 12.0 mm width.

Boundary dimensions

SpecificationValue
Bore diameter d (mm)17.0
Outside diameter D (mm)40.0
Width B (mm)12.0

Boundary dimensions fix what fits the shaft and housing. Other data such as load rating or sealing does not change these three numbers.