How to choose which scale and gauge to use for your train set


When it comes to model trains, size does matter! CHRIS LEIGH explores the differences between the most popular gauges.

If you’re going to build a model railway you need to have at least a basic understanding of gauges and scales. This is especially true because the model railway hobby has got into the habit of indiscriminately mixing up the two. 

What is gauge?  

‘Gauge’ is the distance between the inside edges of the running rails. On the UK main line network, the gauge is 4ft 8½in. In model terms, there are three main gauges for ready-to-run models and train sets sold in the UK.  

You’re probably familiar with the gauge used in train sets made by Hornby and Bachmann, which is 16.5mm gauge, known as ‘OO’ (pronounced ‘double-O’).  

A smaller gauge, in train sets manufactured under the Graham Farish label, is 9mm gauge, known as ‘N’. This has the advantage of allowing more complex layouts in a smaller space, but there is little difference in price due to the more complex and delicate assembly of the smaller models.  


What is ‘O’ gauge?

There has been growth in recent years in the availability of ‘O’ gauge ready-to-run models.  

‘O’ gauge was the historical beginning of railway modelling and train sets in the 1920s; but the gauge almost died out and became virtually restricted to kits and scratch-building, as ‘OO’ gained in popularity in the smaller post-war homes. 

There is no train set base in the current ‘O’ gauge market so few newcomers are likely to encounter it.  

However, in certain circumstances ‘O’ gauge models may be more suited to the partially sighted and those who would have difficulty in handling smaller models. 


What does ‘scale’ mean? 

The term ‘scale’ is not specific to railway modelling and simply relates to the proportions of a model when compared to the real thing. It may be simply expressed as 1:76 (76 models laid end to end would be the same length as one real one), which is the scale used for most ‘OO’ gauge models. This can also be expressed as a measurement, in which case it’s 4mm:1ft - an unfortunate mixture of metric and imperial. 

Here is a table of the main gauges and scales that you are likely to encounter. If you’re new to the hobby, focus on those in bold.  


Have you subscribed to Model Rail?

For more explanation and advice about the model rail hobby, subscribe to Model Rail magazine and get in-depth informative articles every month. Get 7 issues for £24.99!

Model Rail is packed full of the latest new model reviews, expert 'how to' projects and inspirational layouts. There's loads to fire your imagination, with great track plans you can build and inspiration from the real railway, not to mention Model Rail's exclusive range of model locomotives.

Click here to find out more about subscribing to Model Rail.