What Are the Different Sizes of Model Trains?

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What Are the Different Sizes of Model Trains?

The size of model trains is based around a scaling system in comparison to the real full sized version. This ensures that when placed next to each other, the train models look as realistic as possible in respect to their shape and size.

When searching on websites such as eBay understanding the size guide and different classifications of train models can be extremely useful. This guide will look at rail transport modelling scale system and how to also go about making a purchase on eBay successfully.

Rail Transport Modelling Scale Standards

There are different railway organisations that have set up a system to classify train models from all over the world; this can make a purchase confusing, especially if buying from outside the UK. Even if visiting the United Kingdom eBay homepage, results can still appear from worldwide sellers – be careful to check if the size of one of foreign models is suitable for your set and tracks size.

The different railway scaling organisations are listed below. There are various sizes because of the distinction between standard and loading gauges (the gauge is the distance between the rails of the track) in each area. More simply, the actual real life trains are different in size and therefore this alters their scaling.

The NEM standards. Known in the UK as ‘Normal European Modelling’ standards. This is the scaling system used in Europe.

The NMRA standards. Equated to the ‘National Modern Railway Association.’  It is the system widely used in the United States and Canada although quite a few of the scaling specifications are matched with the NEM standards.

Live Steam. Live steam models are not regulated by an official standards body. The majority of live steam train models will scale in accordance to NEM or NMRA standards so check individual models accordingly.

British. The British system is based on the narrower loading gauge used within the British Isles. Because of this many British train models are not often found elsewhere in the world.

All of these modelling standards are defined by alpha numerical symbols. For example the British system uses the following symbols as part of its scaling system: N, TT, HO, OO, Z. N, G, EM, P4, O14, O or S7. Each one designates into a certain ratio that in turn fits in with the relevant gauge size. Looking into these further can help when coming to make a train model purchase.

Common Sizes of Model Trains

In the UK, some model trains are more commonly bought and sold than others. eBay is a good website to determine the popularity and market depth of certain sizes of model by checking how many trains have been listed for each size. This table below will look at some of the most common found train model sizes in the UK.

Gauge Type
Gauge Size (mm)






The most popular scale size in the UK is the OO gauge. Many ready-to-run sets are issued in this size. They run on the same tracks as HO gauges.





This is accepted as the most commonly used scale in the world. Many US train model kits may use HO gauges so look out for this if buying from an American seller on eBay.






The N scales are a smaller gauge size for train models than the OO and HO types. Some train model collectors choose smaller sized gauges so that they can fit in more track length into their designated space.






The O scale is a traditional gauge which is still popular due to their fine detail and nostalgic value over their modern relevance.  The gauge distance is bigger than other types of scales.

Another way to classify train models is by the numerical scale value, which is the size of the model in relation to a real train.

The 4mm scale is called as such because every 4mm is equivalent to 1 foot of the full sized model.  It is sometimes displayed as 1:76.2 and is perhaps the most widely used system in the UK. The scaling system changes in conjunction with larger or smaller models. For example, the HO gauge is the scale equivalent of 3.55mm to 1 foot (1:87) which is smaller than the OO scale.

Buying a Model Train on eBay

Understanding the differing sizes and scales of model trains can be an excruciating business; differing standards set from various times in history and from different parts of the world has seen to this. To avoid any signs of confusion, the best piece of advice is to ask as many questions as possible when coming to make a model train purchase. Reading up on the internet from railway transport experts may also provide some much needed clarification.

In this sense, using eBay is a smart way to shop for model trains. If the size of your track gauge is known then the listings on the site can be arranged to just include these compatible trains. A lot of railway model enthusiasts will sell their trains on eBay also and in this sense, being able to receive first-hand advice from a primary source can be invaluable.

Useful eBay Buying Tips

eBay is the fashionable place to go for those looking for an extra cheap bargain or an item that may be difficult to find elsewhere. Consider the fact that the massive amounts of goods being bought and sold every day are mostly being managed and controlled by ordinary people; in this respect certain ploys can be utilized to try and find the best deals. Below are a few unconventional tips that can make using eBay a highly successful and cost effective venture.

Take advantage of any spelling mistakes that may have been included in the item’s listing. Less people viewing these results will increase the chances of winning an auction and for a cheaper price at that.

Keep checking auction items that may have little interest in them; sellers frequently list some item’s for a small starting price to harbour interest. If these items go unspotted or bidding is sparse, then a last minute bid can secure the purchase for a remarkably low amount.

Some auctions will end at inappropriate times for most people to keep interested in. For example an end time of 4.30am on a Monday morning (where the majority of the U.K will be asleep preparing for a week at work) can allow for sneaking in with a late bid to secure the purchase with little or no competition. 

Bidding in an eBay auction requires a maximum amount to be entered. This is maximum price that eBay will automatically bid to on your behalf. If anyone else exceeds this maximum bid then they will be in control of the item unless bettered. A good tip is to bid irregular and uneven amounts, for example bidding £13.04 for the model trainwill see of others who may have stopped at just £13.

A handy time saving tip is to set up a ‘favourite search.’ To do this, simply type in the desired item and then click the ‘Save This Search’ link. The option for an email to be sent automatically to your inbox as soon an item matching this saved description is listed can be selected. This is useful when a search for a particular model train is unsuccessful. This can also provide an advantage over other potential buyers as a bid or direct purchase can be made as soon as it is listed. 


Railway modelling sizes differ between regions of the world yet due to the popularity of collecting train models finding models compatible with UK sets will not be too difficult.

Use this guide to be accustomed with some of the different size definitions in this guide and swat up even more on the particular sizes needed by reading different websites. By shopping on eBay many model trains can be pinpointed and purchased safely at affordable prices.

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