Nominal size H0

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Size comparison of a model railroad diesel locomotive on a scale of 1:87 with a euro coin
Märklin central ladder track system in an exhibition facility

The nominal size H0 (pronounced: nominal size Ha-zero or nominal size half-zero), also common in England and North America under the term 3.5 mm scale , is one of the standards of European model railways (NEM) and the standards of the National Model Railroad Association (NMRA ) standardized size for model railways . The standard gauge with a prototype gauge of 1435 mm has a model gauge of 16.5 mm and is colloquially referred to as gauge H0. The scale is 1:87. It has its origin in the nominal size 00 , which is now standard instead of the nominal size H0 in England.


Detail of a model railway system of the Rhaetian Railway (RhB) in the H0m gauge
Detail of a diorama with a Wismar rail bus in the H0m gauge

Development of the market position

At the beginning of the 20th century, the nominal size 0 (pronounced: nominal size zero) was introduced for model railways . The standard gauge with a prototype gauge of 1435 mm has a model gauge of 32 mm between the rail heads. The scale is usually 1:45.

Even before the Second World War, efforts were made to develop a table train about half the size from the nominal size 0, which on the one hand would be better suited for small apartments and on the other hand should reduce manufacturing costs. The forerunners of today's H0 nominal size were developed from these efforts.

The standard gauge with a prototype gauge of 1435 mm today has a model gauge of 16.5 mm. The scale is 1:87. After the Second World War , the nominal size H0 replaced the market dominance of the nominal size 0 and became the market-dominating gauge itself.

Neglecting a few details, today the nominal size H0 can be referred to as half the nominal size 0, whereby it should be noted that the nominal size H0 was initially designated as nominal size 00 . The designation of the nominal size 00 still exists today and has evolved into the standard in England with a different scale instead of the nominal size H0. The standard gauge with a prototype gauge of 1435 mm has a model gauge of 16.5 mm; the scale there is 1: 76.2.

As early as 1922, the Bing company in Nuremberg had brought out a "table track" on sheet metal slope track with a gauge of 16.0 mm for a few years. This railway was first available with a clockwork drive, and from 1924 with an electric drive.

At the Leipzig spring fair in 1935, the Trix Express, an electric table train, also with a gauge of 16.0 mm, was presented, which was then designated for the first time as nominal size 00 (pronounced zero-zero). Märklin followed with its table train in nominal size 00 at the Leipzig autumn fair in 1935. The tin toy manufacturer Kibri presented buildings and accessories in a suitable size.

TRIX Express offered a three-rail, three-conductor track on a Bakelite body, which for the first time enabled independent two-train operation on one track. At that time, TRIX still called the scale 1:90. The Märklin track on sheet metal in nominal size 00, which appeared more than ten years after the Bing table track, had a similar appearance to the previous Bing track. At Märklin, however, the rails were lashed separately onto the sheet metal slope, while the bing tracks were simply stamped out of the slope part, i.e. the rails and slope were stamped from a single sheet metal part.

With the introduction of the cardboard sleeper track in 1953, TRIX Express increased the gauge to 16.5 mm.

Market position today

The nominal size H0 is the most widely used nominal size today. In Germany it has a market share of around 70%.


Continental Europe

For the nominal size H0, the following model gauges are specified in the European Model Railways (NEM) standards on a scale of 1:87 :

track designation Model gauge Prototype gauge (selection) Use with prototype gauges
H0 Standard gauge 16.5 mm 1435 mm from 1250 mm to <1700 mm
H0m Meter gauge 12 , 0 mm 1000 mm from 0850 mm to <1250 mm
H0e Narrow gauge 09 , 0 mm 0750 mm, 760 mm and 800 mm from 0650 mm to < 0850 mm
H0i (H0f) Field railway 06.5 mm 0500 mm and 600 mm from 0400 mm to < 0650 mm
H0p Park lane 04.5 mm 0381 mm from 0300 mm to < 0400 mm

North America

For the nominal size H0, the following model gauges are specified in the 1:87 scale in the standards of the National Model Railroad Association (NMRA):

track designation Model gauge Prototype gauge
H0 Standard gauge 16.5 mm 1435 mm (4 feet 8 12 inches )
H0n3½ * Narrow gauge 12 , 0 mm 1067 mm ( 3 12 feet)
H0n3 * Narrow gauge 10.5 mm 0914 mm (3 feet)
H0n2½ (H0n30) * Narrow gauge 09 , 0 mm 0762 mm ( 2 12 feet or 30 inches)
H0n2 Narrow gauge 07 , 0 mm 0610 mm (2 feet)
* Currently (as at the beginning of 2009) not subject to the currently valid standard of the National Model Railroad Association (NMRA)

Manufacturer (selection)

Märklin H0 models of the BR 103
Märklin H0 crocodile from 1959

Major international manufacturers and brand names

Smaller country-specific manufacturers and brand names


Manufacturer and brand names with a decisive contribution to the nominal size H0

  • Trix and Märklin (then 00 gauge, today H0 gauge)
  • ADE and Röwa , later Roco (detailed vehicle models for the H0 gauge)
  • Egger Railway (gauge H0e)
  • BEMO (gauge H0m)
  • Peco (track material)

Track systems of the H0 gauge

Today there are three electrical track systems within the nominal size H0, the H0 gauge. The two-rail, the middle-rail and the three-rail track system. The two-rail as well as the three-rail track system is operated with direct current, the central conductor track system with alternating current. However, this assignment is only determined by the offers of the manufacturer and is not a technical requirement. It should be noted that digital operation, which has been possible since the mid-1980s, is becoming increasingly important.

Deviations in scale

Length scale

Scale model of an ABm 225 from the model railway manufacturer Roco
Despite the shortened length of the small railway control car, there is a risk of collision in the area of ​​the overhead line mast in a curve with a radius of 360 mm on a home layout.

Locomotives and freight wagons are usually produced by all manufacturers on a scale of 1:87. Passenger carriages with a prototype length of over 26 meters are in the premium segment on a scale of 1:87; Depending on the manufacturer and price segment, models with shortened lengths are also offered, usually in a 1: 100 length scale in entry-level ranges.

A typical modern passenger coach is 26.4 m long in the prototype and has a length of 303 mm on a 1:87 scale. Since the smallest radius of most H0 track systems is just 360 mm, these models have very large lateral overhangs, which on the one hand are considered unattractive and on the other hand must be kept free when designing the layout (see picture on the right). In addition, the shortening reduces the overall length of the train, so that more cars can possibly be accommodated on the layout.

The so-called length scale was initially set mainly at 1: 100 at the beginning of the 1970s, which results in a length of 264 mm for the usual UIC-X cars . Passenger carriages, which are already below this length at a scale of 1:87, have been offered in full since then. Previously, almost all models were inconsistent and mostly shortened even more. About ten years later, manufacturers began to produce full-length models.

Since the end of the 1980s, Fleischmann, among others, introduced an intermediate scale of 1: 93.5, which was received very ambiguously by the market, just as the market leader Märklin followed suit in the mid-2000s. The crooked length scale arises from the true-to-scale length of UIC-Y-cars , which have a model length of 282 mm with a prototype length of 24.5 meters. Individual wagons also have slightly different scales.

Further deviations

The endeavor to make the models as true to scale as possible has its limits in the area of ​​the wheels and rails with commercially available systems. The commercial models of vehicles have wheels that are too wide and have flanges that are too high and too thick. In the case of the rails, this sometimes leads to unscaled track profiles; in the case of switches and crossings, the wide gaps between the focal points leave a lot to be desired in terms of model accuracy. In the case of vehicle models, too, distortions of scale often result from the immeasurability of the wheel-rail system.

In order to get to scale models in the wheel-rail sector, a minority of model railroaders - initially in Great Britain and since the mid-1990s in the USA and Europe - began developing wheels and switches that were exactly to scale under the name Proto87 or . P87 . In Germany this development was promoted under the name H0pur .


In North America, and partly in the United Kingdom, the letter O is often used instead of the number 0 to denote the nominal size or the gauge .

The designation for narrow-gauge railways in the United Kingdom is inconsistent. In this article, the notation is used consistently as follows: H0 for the nominal size, minus sign for the separation of the model gauge, comma as a separator for the decimal place in the number of the model gauge. Example: H0-9 .

Web links

Commons : H0 gauge  - collection of pictures
Commons : Gauge H0m  - collection of images
Commons : Gauge H0e  - collection of pictures
Commons : Gauge H0n3  - collection of images

Individual evidence

  1. Federal Association of German Railway Friends (BDEF), model railway market analysis 2007, nominal sizes in Germany, all model railway users ( Memento of the original from December 22, 2015 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot /