This or That: Gauge versus Scale

This particular series is going to be a hybrid of the Word of the Week and Spotlight series, but we’re going to take TWO words and explain what they mean. These are going to be two words that are similar and easy to mix up, but are actually quite different in their definitions.

In this post, we’re going to discuss “gauge” and “scale,” both of which are related to model trains.

Gauge refers to the width of the track. Certain tracks can only hold certain sized trains. You can measure this by either choosing the distance between the rails on the track, or the distance between the wheels on the train car.

Scale refers to the size of the model train. This is often portrayed as a fraction or a ratio, and it’s the relationship between the model and the real-life prototype.

Now, here’s the important (and confusing) part. The scale is simply the fractional equivalent of the gauge. Before you start shaking your head and walking away – think about it. It makes sense. The gauge is determined by the width of the wheels. That obviously determines what size the train can be. The size of the model train in relation to the size of the actual train determines the scale. See how they’re connected?

The most popular gauges are (from biggest to smallest): G, O, S, HO, N, and Z.

Here’s a chart, with the width being the distance between the rails:

Gauge Width Scale
G 45mm 1:22.5
O 32mm 1:48
S 22.5mm 1:64
HO 16.5mm 1:87.1
N 9mm 1:160
Z 6mm 1:220

(Here’s where I got the above information. This is literally the only page that could explain these words to me in plain English. It has some of the lesser known gauges in there as well, so it’s worth checking out on top of this post.)

As you can see, the width is generally measured in millimeters so it’s as specific as possible. I usually don’t pay much attention to the numbers for the scale because they aren’t necessarily important to me as a seller. I DO try to determine the gauge, however, because that’s what most people will search for when they’re looking for pieces to match a set they already have.

Did that help you to understand the difference between gauges and scales? Do you have any questions? Are there any other words that you often mix up?


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