What is G Scale / Large Scale?

Latest update: 3 November 2016

What is the Difference Between Gauge and Scale?

  • Gauge: Distance between the rails. Some examples of prototype track gauges:
    • 1435 mm = “Standard gauge” = Most railways today are standard gauge.
    • 1000 mm = “Meter gauge” = Commonly used gauge for narrow gauge railways in Europe.
    • 914 mm = “Three foot gauge” = Commonly used gauge for narrow gauge railways in America.
  • Scale: Ratio of the model to the prototype.
    • 1:1 = The real thing!
    • 1:87 = “H0 scale” = the most popular scale for model trains worldwide. Trains are 87 times smaller than the real thing.

The Smaller Scales

In the smaller scales like for instance H0 and Z, the scale is the most important identifier, the track gauge not so much. If you mention H0, most people will know it’s a scale of 1:87. If you mention Z scale, they might know it’s 1:220 scale. As it will become clear further down this page, the same does not apply to G scale…

Most scales are assigned a letter or number for identification and marketing purposes. The starting point for most scales is a scale in relation to a standard gauge prototype. For meter gauge prototypes in Europe, the letter “m” is often added to the name. American three foot gauge is often identified by adding “n3” to the name. There are more guidelines and more letter additions, but I just wanted to give you an idea of the philosophy behind the naming system.

Let’s apply this logic to 1:87 scale. “H0” uses a model track gauge of 16,5 mm to represent standard gauge prototypes in 1:87 scale. Meter gauge prototypes in 1:87 scale are identified as “H0m” with a model track gauge of 12 mm. Three foot gauge prototypes in 1:87 scale are identified as “H0n3”, with a model track gauge of 10,5 mm.

Origins of G Scale

G scale was started by LGB in the 1960s. Their idea was to model European meter gauge prototypes on a 45 mm model track gauge, resulting in the scale of 1:22,5.

LGB’s 1:22,5 scale trains on 45 mm track quickly became popular, and other manufacturers joined the party.

Evolution of G Scale

Other manufacturers entered the market, and new scales were introduced and made popular.

  • 1:19 – Scale used to model British narrow gauge models on 32 mm or 45 mm gauge track. 32 mm is more accurate, 45 mm is popular for its compatibility with G scale. Scale is called “16 mm scale”. The name is confusing, just ignore it.
  • 1:20,3 – Accurate scale to model American narrow gauge prototypes. The scale was introduced to move away from the 1:22,5 scale that was previously used (and still is) to – incorrectly – model American narrow gauge. 1:20,3 is increasingly popular, and several manufacturers committed to the scale. There’s still a shortage of affordable, mass produced rolling stock though. Popular with scratch builders.
  • 1:22,5 – Accurate scale to model European narrow gauge prototypes. Still very popular, with plenty of affordable models. Small series, high end rolling stock also available. Popular with scratch builders.
  • 1:24 – An attempt to model American narrow gauge on a 45 mm model track gauge. Becoming less popular.
  • 1:29 – Some American manufacturers went to 1:29 scale for standard gauge trains instead of the more accurate 1:32. One of the reasons being that a standard gauge car in 1:29 comes out in similar physical dimensions to a narrow gauge car in 1:20,3 / 1:22,5. This makes them look good running together. 1:29 is the most popular scale in America, with a large variety of mass produced rolling stock for reasonable prices.
  • 1:32 – Accurate scale to model standard gauge prototypes. Existed long before G scale, but lost popularity. Revival in recent years. Most of what is available are high end models produced in smaller quantities. Scratch building necessary if you don’t have the money.


The NMRA (U.S.) and MOROP (Europe) organisations tried to standardize some of the larger scales. The NMRA defined the “F” scale for American narrow gauge trains, MOROP defined “NEM” standards for European prototype trains.

  • F Scale = 1:20,3 [NMRA – American]
    • F = Standard gauge trains modelled on 70,64 mm model track gauge
    • Fn3 = Three foot gauge trains modelled on 45 mm model track gauge
  • 2 Scale = 1:22,5 [NEM – European]
    • 2 = Standard gauge trains modelled on 64 mm model track gauge
    • 2m = Meter gauge trains modelled on 45 mm model track gauge
  • 1 Scale = 1:32 [NEM – European]
    • 1 = Standard gauge trains modelled on 45 mm model track gauge
    • 1m = Meter gauge trains modelled on 32 mm model track gauge

So if we use the 45 mm model gauge track as a common identifier, there are three major modelling scales that are prototypically correct for this model track gauge: 1:20,3 scale narrow gauge, 1:22,5 scale narrow gauge, and 1:32 scale standard gauge.

G Scale? Large Scale? Gauge One?

Today, G scale is a marketing term generally used for model railroad items scaled between 1:19 and 1:29, with the 45 mm track gauge in common. It has become widely accepted to use “G” on for example the box of a 1:29 scale train, even though “G” originally was 1:22,5 scale only.

So is it wrong to use G scale to describe all of the larger scales? Yes and No. Technically it is incorrect, but everyone is doing it, so… Some manufacturers use the term “Large Scale” instead of G scale, which makes more sense.

1:32 scale is usually not considered to be a part of G scale. 1:32 is more commonly known as “Gauge 1” or “Gauge One”. It can be argued that those names are incorrect, as 1:32 scale is defined as “1 Scale”, and should not be identified by its gauge.

Scale Fidelity

Many manufacturers didn’t / don’t care about scale too much, their philosophy was / is to make what looks good (in comparison to other rolling stock).

On forums you will often see the term “rubber ruler”, which is a joking way of saying that some manufacturers take the freedom to change the dimensions of their models to their liking.

In such cases, typically the length of a model is shortened to make it go around the tight curves often found in garden railways. Not everyone has the space in their backyard for prototypical large curves, so compromises need to be made…

Scale, Who Cares?

Some people care, others don’t… Purists want to model a existing railway to a perfect scale, others are happy when all their trains are about the same size and look good running together.

Run what looks good to you.