Model Train Scale

You’ll hear model railroaders utter the terms “scale and gauge” in one breath.  This can be confusing.  Now here’s your chance to separate the scale from the gauge — once and for all!

For the beginning model railroader, these terms may appear more intimidating than they really are.  To make matters worse, they are used interchangeably. So, let’s tackle them one at a time, and you’’ see exactly what they mean — and how you they can become a part of your new language.


In this hobby you’ll hear a lot of people bandy about the term scale.  Scale, in a nutshell, is the ratio of the model train to the life-size or “prototype” train.

Scale actually means exactly what the name implies.  That the model you’re running or building is a “scaled down” replica of the life-size version.  Scales are usually indicated as a ratio, such as “1:48”, meaning that a real item 48 feet long would be a model only 1 foot long (which is “O” scale). The different letters assigned to the scales are just another way to keep track of the different ratios.


Gauge, though sometimes spoken in the same breath as scale, is slightly different.  Gauge refers to the width of the tracks on which your train runs. For any scale, there can be many “gauges.”

Let’s stop here for just a moment to consider the importance of gauge, especially.  The reason this hobby is popular is partially because the manufacturers of these trains are precise enough with their processes to ensure that the trains the actually fit on the track.

Imagine this scenario if the makers of different train equipment used all sorts of various sizes of gauges.  You bring home a new locomotive to put on your track. And it doesn’t fit.

When you talk track, it has to be absolutely accurate. If it’s just a little off — you may not be able to see it at a glance – you’ll have problems. We don’t want that, do we?

Large-scale trains

This is the term the modelers used to describe, surprisingly enough, the larger selections.  These models come not in just one scale but several, ranging from 1:4 down to 1:38.

Many of these trains are used by those aficionados who run their systems outdoors in their backyards.  The locomotives chugged along carrying their cars through large flower and herb gardens.

Large scale trains run on a variety of gauge tracks, from 32mm (smallest gauge in this category), up to 254 mm (for 1:4 scale) and even larger. Gauge “1” track is 45mm, very popular and used with a variety of scales, Gauge “2” track is 50.4mm (not used very much) and Gauge “3” track is 64mm between the rails. Gauge 3 is one of the original standards for model railroads created in 1909. There are many other gauges, these are a few that have been “named.”

O scale is 1:43.5 in Great Britain and France, and 1:45 in Germany and 1:48 in the US. Lionel is one of the manufacturers of trains and equipment at this track gauge.

Smaller Scale Model Trains

So, just how small of a scale is available?  I’m glad you asked.  Let’s find out just how small these trains can get!

OO gauge is very popular in the UK. It’s scale is 1:76.2. Double-O scale uses the same track as HO. A 50 foot locomotive would be 7.8 inches at this scale.

There’s the HO gauge. HO literally stands for “half of O”.  This class of trains is built to be exactly one half the size of “O” gauge models, resulting in a scale of 1:87.  Now, that makes our 50-foot life-size prototype 6.9 inches in this scale.

On first impression, you make think that this is extremely small.  But, the HO train models are an ideal size to allow a satisfying layout in a smaller space.  But, at the same time, these cars are large enough to display detail.  And they really aren’t too small to work with.

It’s no wonder that HO is the most popular of all model railroad scales. More than two-thirds of modelers rank it as their favorite size!

But we go even smaller than that when we view the “N” scale.  This scale, with a ratio of 1:160, has a gauge of 9 mm between the rails.  It’s preferred by those who don’t have the room they’d like for their layout.  Those individuals who love extensive scenery also appreciate this gauge.

Finally, the smallest commercially produced scale to date – “Z” scale trains.  Yes, they are small!  Their scale to the prototype locomotive is 1:220.  Yes. Imagine that.  This size means that our 50-foot locomotive is only 2 ¾ inches long in the “Z” scale.  The track gauge for this model’s scale is 6.5 mm.

There you have it. There’s more scales and gauges than can be covered here. You will find a scale to fit your budget of space, keep you interested, and meet others who also enjoy the same.

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About Scott

Model Train enthusiast, engineer, inventor, fitness nerd, computer geek, ex-husband, entrepreneur.
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8 Responses to Model Train Scale

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