It is not just a matter of picking a letter Z, N, HO, S, O or G) you happen to like. Those letters designate scale from smallest to largest. And so much hinges on which you pick.
For instance, say you have a standalone 8’X12’ shed you could build into a model railroad layout. Depending on its size you could accomplish a lot (Z or HO), but remember, a G Scale boxcar is 16 inches in length, you could hook six together in an 8-foot distance.
Conversely , the level of detail in a G Scale engine is far more precise than the locos of its junior brethren. That means that pencil-sized steam pipe in G Scale is down to the diameter of a gauge 2 wire. No matter how realistic, your wife is probably not going to be interested in having it run on track around your dining room table on a permanent basis.
G scale tips the “scale” at 1:24. That means a real engine is 24 times the size of the model, or a 75-foot real life engine is 4o inches long in G.
O Scale comes in at 1:43.5, just under half the size of G Scale. In earlier days this was the Toy Train size. Though toy trains use this gauge, they are often nowhere near scale. The same 75-foot engine is down to 18.75 inches in Scale.
S Scale measures up to 1/64th the size of the real engine and contrary to what many model railroaders believe, there is a large segment of the S gauge community who build and operate perfectly scaled models with exacting precision and detail. A 75-foot-long locomotive comes in under 14 inches in S Scale.
Drop down 10% in size from S and you are in the popular HO Scale range 1:87. HO gets its name from the fact the 1:87 size (remember that is 1/87th the size of real life) is half the size of O Scale. That 75-foot engine is now 10.5 inches in length. This is the most popular choice for modelers. HO trains balance size, precision and durability which probably figures high in its popularity.
But railroad tie for railroad tie, N Scale fits today’s practicality barometer (budget, room size and “cuteness” test. Entire N Scale layouts can be done on a three-foot by eight-foot hollow-core door.
That 75-foot engine is now down to 5.5 inches in length 1/160th of real life. On an 8-foot track you can line up 24 boxcars coupler-to-coupler. Jump up to O Scale and you’ll be able to park six box cars.
The real space king is Z-Scale, the Lilliput of model railroading. That 75-footer now measures four inches in length.
Here is an Army Base circled by a Z Scale train in less than 30 seconds.