O Scale Model Railroads & Trains

O scale refers to 1:48 scale model trains which run on 1 1/4" gauge track. The letter O stands for less than one, since O scale trains were smaller than standard or 1 scale. O scale trains were first produced in the 1890s and this was the primary scale used for model railroads prior to World War II.

Ives, Märklin, Lionel, and American Flyer were all model railroad companies who offered some of the first O scale model trains. These trains ran on three-rail track, with the middle rail delivering power to the train. O scale trains were most popular during the '30s, as they were more affordable than standard-scale trains. After World War II, HO scale eclipsed O scale in popularity as the smaller scale, half the size of O, appealed to people with smaller homes and less space for model trains.

O scale enjoyed a resurgence of popularity in the '90s, when the television show "Thomas the Tank Engine" revived interest in model trains. Today, Lionel is the leading manufacturer of O scale model trains, including continued production of American Flyer and K-Line trains. MTH is also a leading producer of O scale model railroad products.

Quick Facts

• The terms O scale and O gauge are often used interchangeably. Hardcore hobbyists will point out, however, that O scale refers to the size of the model trains while O gauge refers to the distance between the track rails
• Variations in O gauge track include narrow gauge versions, designated by On3, On2, and so on, as well as track that has been adjusted to accommodate tighter turns, such as O27 gauge track
• Modern O scale hobbyists prefer two-rail O gauge track, as it appears more realistic. Three-rail track causes the models to ride high on the rails, reducing the realistic look of the layout