Comparison of S with 4mm and 7mm scales
S scale is 1/64th full size. By comparison 4mm scale ( 00, EM and P4) models are a factor of 76.2 smaller than the prototype whereas 7mm scale (0 gauge) models are 43.54 times smaller than real life. In other words S scale is about 19% larger than 4mm scale, making it easier to see and incorporate more detail in models with about 69% more volume for the motor, gears and weight. However, being only approximately two-thirds the size of 7mm scale, there is not the same problem with layout size as it occupies less than half of the area of 7mm scale.