Scale and Gauge

Gauge simply means the distance between the rails. For Gauge One this is 45mm. Regardless of the scale of your model, if it is Gauge One then the wheels are 45mm apart and it will run on Gauge One track. Gauge One, or Gauge #1, or 1-gauge, is often also referred to as G Scale or G Gauge.

Scale refers to the difference in size between the original and the model. If, for example, a locomotive is 24 metres long and a model of it is made which is 1 metre long, then the model is said to be in 1:24 scale. Models for Gauge One are made in many different scales because the originals come in many different sizes – and the tracks they run on are also different sizes – and they have to be shrunk down to fit on 45mm track. Some modellers like to run trains all of the same scale, for a more "authentic" look. Others are happy to mix scales, with some trains looking a bit bigger and others looking a bit smaller.

But the most important thing is to have fun with your trains, whether you're free and easy or a stickler for authenticity.

Track Styles

Because real-world tracks come in different sizes – different gauges – and Gauge One track is all 45mm, manufacturers represent the different track sizes by varying the distance between the sleepers. If you shrink a broad-gauge track down to 45mm, the sleepers will be closer together than if you shrink a narrow-gauge track down to 45mm.

There are many different gauges of track in the real world, but for practical purposes most model manufacturers supply only two styles: Standard Gauge and Narrow Gauge. Standard Gauge represents American mainline railways, while Narrow Gauge represents the narrower railways commonly found in Europe (and also in American shortline railways.)

In these two styles, the rails are still 45mm apart. The only difference is that the sleepers are closer together in Standard Gauge than they are in Narrow Gauge. As always, your choice depends on what looks good to you.

Rail Profiles

The rail "profile" is the shape of the metal rail. For the purposes of model railways, "profile" refers just to the height of the rail, i.e. how thick the rail is from the bottom to the top surface that the wheels run on. Again, real-world rail profiles vary, but model manufacturers usually supply only a few different styles. The most popular rail profile for Gauge One railways is 332/1,000th of an inch (three hundred and thirty-three one-thousandths of an inch). This is the measurement from the bottom surface to the top surface of the rail. To make it easier to say, this is called Code 332. Another popular profile is Code 250, which is 250/1,000th of an inch (in other words a quarter of an inch).

Code 250 rail is slightly thinner (top to bottom) than Code 332. Some modellers prefer Code 250 because they think it looks more realistic. But many others prefer Code 332 because it is considerably more robust, which is particularly important for outdoor railways.