Model Railroad Scales
Model railroaders have many scales to select from when planning their model railroad layouts. Scale refers to the ratio between prototype and model. For example, on an HO Scale or 1:87 model railroad layout, rolling stock, scenery and buildings will be 1/87 the size of the prototype, or real life size.
The most popular model railroad scale today is HO Scale, or 1:87. The smaller scales are N scale (1:160) and Z scale (1:220) and are ideal scales to use where you have a limited amount of space in which to build your layout. On an N scale layout everything would be 1/160 the size of full scale, and on a Z scale layout, things would be 1/220 the size of full scale. The smaller scales call for better vision and hand eye coordination when assembling buildings and working on rolling stock.
The larger model railroad scales are S Scale (1:64), O scale (1:48) and G scale (1:24). Many of the old Lionel trainsets of the 50's and 60's were O scale, and today O scale is still a very popular scale in model railroading. G scale is known as Garden Scale and is extremely popular for outdoor model railroad layouts where it is easy to keep the natural scenery in proportion to the rolling stock.
You can also model O scale, N scale and S scale as narrow gauge. They are called On3, Nn3 and Sn3. Again, the only thing that differentiates them from their parent scale is the use of narrow gauge track. It is possible to use 30" gauge track (30 inches between the rails) and 2' gauge track (24" between the rails). Some popular scale/gauge combinations are On30 and On2.