How big is a G scale train? It depends, and it also depends on whether you’re asking about the size of the train itself or the track. Let’s tackle both questions.
In G scale, one foot in real life is approximately half an inch on the model. In real life, a box car is around 40 feet long. So a G scale model of a box car works out to approximately 20 inches long. Scale is a ratio of the model in relation to the real thing.
How big is a G scale train itself?
You can estimate the size of a G scale train by rounding down to a foot and a half. Estimate the length of a locomotive at about two feet and each car at one and a half feet. So a G scale train from a starter set that consists of a locomotive and three cars will be around six and a half feet long. A set with four cars will be around eight feet long.
How big is G scale track?
Model train makers sell track in standardized sections of curved and straight track. The curves are standardized based on measurements that tend to work well. There’s no reason someone couldn’t make a circle of G scale track that’s 18 inches in diameter, but few, if any trains would run well on it. So while it’s possible, it’s not really a very good idea.
G scale track is measured in radius, not diameter. LGB’s smallest track has a two-foot radius, so a circle of this track has a four-foot diameter. Straight sections tend to be 24-32 inches in length.
This means an oval of G scale track will typically be a minimum of four feet wide in one direction and six feet wide in the other. Even a very modest G scale setup takes up a lot of space, which is why it’s popular for outdoor layouts. Many people can swing a four-foot circle around a Christmas tree, but for something more elaborate than that, you need a lot of space. This typically means a basement or attic, or outdoors.
This is why G scale is the most popular scale for outdoor trains, by far, but a distant fourth, at best, for indoor layouts. For people who want large indoor trains, O scale and S scale are more practical.