When beginning a model railroad, the enthusiast must first decide what kind of budget is in place for this endeavor. After that has been decided, the next question is what size the model layout will be. The size of the layout, in model railroad terms, is called scale and gauge. Briefly, scale is divided into 4 main groups (HO, N, O and S) and is actually the ratio of the model to the real thing. Gauge is distance between the rails. We will go more in depth beginning with Scale.
As stated before, scale implies a ‘scaled down’ version of the actual train. Using the scale identifiers: O scale (formerly known as ¼ inch scale) had a ratio of 1:48 with the real trains. HO scale is metric (3.5mm scale) and is 1:87.1. The S scale, exclusively from manufacturer American Flyer, falls between O and HO. N scale is at a remarkable 1:160, but that isn’t the smallest. The smallest is Z scale at a ratio of 1:220. When deciding on a scale, HO and N are the most popular, with a large selection of quality products available.
Gauge, on the other hand, is another matter entirely. Gauge for model railroading, as well as real railroads, refers to the distance between rails. Normal real track gauge is 4 feet 8 ½ inches.
Later on when the enthusiast has more experience, terms like Proto87 and Finescale will be heard in reference to scale and gauge. These reference differences in track and wheel standards and practices but have very little effect on the beginning model railroader.