N scale

N scale is a popular model railway standard, allowing hobbyists to either build layouts that take up less space than HO scale, or to pack longer runs with more detail into a similar amount of space. The name is an abbreviation for Nine millimeter. It is also sometimes called "2mm to the foot," in reference to its scale.

N scale uses 9 mm-gauge track, and a scale of 1:160 worldwide, except for the United Kingdom where a scale of is 1:144 is used because of the problems early on in fitting mechanisms into smaller British trains.

Although trains and accessories of similar gauge and/or scale existed as early as 1927, modern N scale appeared in 1962. Unlike other scales and gauges, which were de facto standards at best, within two years N scale defined the gauge, voltage, and polarity of track, as well as the height and type of couplers.

N scale is second only to HO scale in popularity as a modelling scale worldwide.

2mm scale

A fair number of modellers in the United Kingdom use 2mm scale, an older standard than N scale. 2mm scale, as the name implies, is scaled at 2mm to the foot (1.152) with a 9.42mm track gauge. Exact scale track and wheels are used rather than the somewhat coarser N gauge standards.