![]()
About Gauge
On the real railroads as well as toy trains, gauge refers to the distance between the outside rails of the track.
Lionel O gauge track systems—which include O, O-27, and FasTrack®—all measure 1 1/4" between the outer rails. Any O gauge car or locomotive can ride on Lionel O gauge track, as long as the curve track used on your layout can accommodate your particular cars (see Minimum Curve section).
Lionel S gauge track (AF FasTrack) is narrower than O, and supports American Flyer and other S gauge cars.
Lionel G gauge track, which is wider than O gauge, supports G gauge cars and locomotives.
Gauge vs. scale
As you now know, gauge refers to track size. Scale, on the other hand, measures the size relationship between a model and its real-world prototype.
Most Lionel O-Gauge trains generally measure about 1:48 scale.
This relationship is approximate for the Lionel Traditional line of cars and locomotives, which typically can run on layouts with tight curves (like O-27 or O-31). Lionel Standard O freight cars and engines, which are made to be as exact as possible to 1:48 scale, oftentimes require a wider minimum curve, such as O-36 or more.
Most Lionel S-Gauge trains measure about 1:64 scale.
This relationship is approximate for the Traditional American Flyer line of cars and locomotives. In the American Flyer S Scale line, cars and locomotives are made to be as exact as possible to 1:64 scale, and they may require a wider minimum track curve because of their larger size.
Lionel G-Gauge trains measure about 1:24 scale.
Sometimes the terms "gauge" and "scale" are used interchangeably even though, technically, they're different.
About Minimum Curve
What is Minimum Curve?
This measurement is very useful in purchasing track, locomotives, and rolling stock that are compatible with one another. For example, assemble O-72 curved track into a circle and you will have a 72" diameter layout. Assemble O-36 curved track into a circle, and you will have a layout 36" in diameter. A locomotive with a Minimum Curve requirement of O-36 will run on a layout with O-72 curves, but a locomotive with a Minimum Curve requirement of O-72 will not run on a layout with O-36 curves.
Recommended Minimum Curve
Lionel locomotives and rolling stock are thoroughly tested to determine their Minimum Curve requirement. In some cases, a Lionel car or locomotive may be able to easily negotiate most, but not all, possible track configurations for that Minimum Curve. For these products, a Recommended Minimum Curve is also given. This larger measurement allows for all combinations of Lionel track and switches.
