It is best to choose a model train set scale that best suits your needs and gives you the effect you are looking for in your model train set layout.

O scale model trains and S scale model trains are large when compared to the more popular HO scale model trains.

O scale is 1:48 size with 1¼” track gauge and a minimum radius of 2 foot (24 inches).

S scale is 1:64 size with 7/8″ track gauge and a minimum radius of 22½ inches. As you can see S scale model trains sets are smaller in size than the larger O scale model train sets.