Please note the image size displayed will vary with screen size and resolution, so will not be displayed to scale. We have added a rule in inches and millimetres along the bottom and on the left side of the image to help you visualise the true size.
The image here shows the relative sizes of model trains made to the main gauges used for modeling standard gauge trains, those being the trains running on the national network of Britains' railways. A suburban passenger steam engine has been used as an example locomotive.
In the top left corner is table which gives the name, track gauge and modeling scale for each of the model train gauges, the last column shows another common description for the scale, expressing the the ratio of millimetres of model measurement to 1 foot length on the real train.
Originally model train gauges were numbered. Gauge 1 models are still available, however a layout for these large size models cannot easily be accommodated indoors. Gauge O, now known by the letter O rather than 'gauge zero' was the gauge of Hornby Tinplate model trains, designed for indoor use. Todays most common model railway gauges are smaller than O and described by letters.
O Gauge models running on 32mm gauge track have recently seen a resurgence in popularity following the introduction of ready-to-run locomotives and wagons by Dapol, Heljan and Ixion. These large models run at realistically slow speeds and allow the use of prototypical 3-link couplings for shunting.
OO, HO and OO/HO models which are designed for a track of 16.5mm have been the most popular gauge in Britain for many years with a wide range of models available at all times. The track is the same as is used for European and American HO trains, hence track is sold as OO/HO, ie. suitable for both OO and HO trains.
OO model trains are made to a scale of 1/76, sometimes described as 4mm (to 1 foot). Look out for other models described as 1/76 scale for directly compatible models. Aircraft models commonly made to 1/72 scale can also be used.
Hornby and Peco Setrack systems are near-identical, using the same standard track lengths and curve radii. Most sections are directly interchangeable. Hornby and Peco track geometry reference diagrams can be found here
HO models are manufactured in Europe and North America to a scale of 1/87 or 3.5mm. These trains use the same track as British OO trains and several model accessory and scenics ranges from Europe made to this scale can be used with OO model trains.
N Gauge is increasing in popularity as it is smaller and requires less space for a layout, often a major consideration in modern homes. The N itself stands for Nine, the 9 milimetres track gauge.
The scale used for N varies, with 1/148 being accepted for British N Gauge, approximating to 2mm to 1 foot, sometimes the description 2mm scale is also used on models for British N gauge railways. European, Japanese and American N gauge models are produced to slightly different scales with 1/160 being the most common ratio.
The range of diecast road vehicles being produced specifically for N gauge has expanded recently, but N gauge modellers will have little difficulty mixing models with scales from 1/140 to 1/160, with 1/144 being another common scale for model aircraft and plastic kits.