Article by Gregg Osbourn
HO scale model trains are what most children receive as Christmas presents. They are small enough to fit into a small space but large enough to be seen and worked with easily. HO scale is currently the most popular scale by far with a ratio of 1/87. O scale is next with a ratio of 1/48. HO scale is preferred by individuals who don't have a lot of room for their layouts or those who love expansive scenery.
The most popular size for a train set are HO scale model trains. You should plan on buying a HO train set unless you have a good reason to need bigger or smaller size. HO scale is by far the most popular in the hobby of scale model railroading, representing about 85% of the model railroaders. N scale is about half the size of HO, and is the second most popular scale, at about 10%. HO scale is large enough to work with easily but also small enough that you can create a large layout within limited space. Most of you who are new to model railways are likely to have already seen HO scale sets.
An HO locomotive is about 1/87th the size of a real one -- you would need 87 HO locomotives lined up end to end to equal the length of a real locomotive of exactly the same type! HO scale is the most popular, and therefore offers the largest market for manufacturers. HO scale is preferred by Continental manufacturers (European and American), many of whom have been around for as long as Hornby has in the UK. While three rail control fell out of favor in Britain it still has a following in Europe and Marklin has persevered the technology.
N scale model trains are most often used by scale modelers who have a space problem. Its small size allows for highly-detailed layouts located in a small bedroom. N scale allows for a lot of action in a small space, but is still large enough for modelers to be able to appreciate the detail of the pieces. It is a scale 1/160 that of the real railroad. Recent progress in manufacturing techniques has increased the detail level of N scale and made it more attractive to modeler who are after realism in their models.