The 'scale' is the proportion of actual size the replica or model represents. Scale is usually expressed as a ratio (e.g. '1:35') or as a fraction (e.g. '1:35th'). In either case it conveys the notion that the replica or model is accurately scaled in all visible proportions from a full-size prototype object. Thus a 1:35th scale model tank is 1/35th the size of the actual vehicle upon which the model is based. Models generally make no attempt to replicate scale weight, only size.
The most popular scales, by far, are 1:35 and 1:72. Other less-commonly used scales for commercially produced kits include: 1:1, 1:6, 1:9 ("Traditional" scale), 1:12, 1:16 (RC tanks, scale model kits), 1:24, 1:25, 1:30, 1:32, 1:48, 1:50, 1:64, 1:87 (railroad HO scale), 1:144, 1:250, 1:285, 1:300, and 1:350. A relatively recent trend led by Tamiya is military vehicle kits in 1:48 scale a popular scale for military aircraft models. The scale was formerly introduced by companies such as Aurora, and Bandai in the 1970s. However, the scale did not gain popularity mostly because of the accuracy and detail of the scale. Scratchbuilt models may be in any scale but tend to follow the most popular kit scales due to the ease of finding kit components which may be used in the scratchbuilt model.
Larger-scale models tend to incorporate higher levels of detail, but even smaller-scale models may be quite intricate.
Military vehicle modelers build a wide variety of models. Tanks and other armored fighting vehicles are the most popular subjects at model contests. Modelers also build ordnance, military trucks and half-tracks, and lighter vehicles such as jeeps and motorcycles. Models may be displayed in stand-alone mode, that is, with no base, or on a decorative base, often with a label of some kind. More elaborate bases may include scale scenery, intended to depict the setting in which the vehicle served. This trends towards the closely related hobby of diorama building.
Modelers tend to focus on vehicles from three eras: World War I, World War II, and the modern era. The first denotes armored vehicles from their inception into combat during the first World War until approximately 1939. Many vehicles of this time period may be considered to be experimental and few made major contributions to the few battles in which they took part.
Models depicting vehicles from the World War I era and the following interwar years are not as numerous as their later world war counterparts, but this is beginning to change in recent years. As of the centenary of the start of World War I, more manufacturers have begun to release kits World War I and interwar subjects: Takom releasing a range of British tanks such as the Mark I and Whippet; Meng providing two variants of the FT-17 and the German A7V and Hobbyboss releasing an interwar Vickers Medium Mark II are all examples of this.
Vehicles used between 1939 and 1945 fall into the World War II category. Even though this era spans the shortest number of years, it is by far the most popular for armor modelers due to the enormous range of vehicles used and the vast improvements in armor technology. During the early part of the war, most armored vehicles were smaller, less heavily armored, and lightly armed. Major tank engagements early on convinced governments on all sides of the need for more survivable and deadlier vehicles. This means that there is a large variety of different subjects which were designed to fulfil different roles under different doctrines.
Any vehicle serving in a setting after 1945 is considered "modern." This encompasses a longer time span and very large number of armor designs from many countries.
Models may also be categorized by place of service, for example, US or Soviet. They may also be categorized by function, for example, combat engineering vehicles, recovery vehicles, etc. In all cases, the national and unit markings on the replica determine the era and user nationality. For example, a model of a Sherman tank, a World War II design, would be considered a 'modern' model if the tank were shown in Israeli markings from the Six-Day War. The same vehicle in World War II US Army markings would be considered a World War II Allied subject.
Models are generally built with historical accuracy in mind, and each model may represent many hours of research effort on the part of the modeler. Frequently, modelers display some of their research work alongside their model.
There is generally some crossover of modelers between the eras, though some focus solely on a specific era, country of origin or operation, or even on a specific vehicle and its variants.