In the United States and Europe, models of standard gauge (1,435 mm (4 ft 8 1⁄2 in)) trains are built to 1:160 scale and made so that they run on N gauge track, but in some other countries changes are made. Finescale modellers also use variants of normal N scale.
In the United Kingdom a scale of 1:148 is used for commercially produced models. In Japan, a scale of 1:150 is used for the models of 3 ft 6 in (1,067 mm) and 4 ft 6 in (1,372 mm) in gauge trains, while a scale of 1:160 is used for models of standard gauge Shinkansen (Bullet Train) models. In the U.S. and Europe, a scale of 1:160 is used for models of trains, irrespective of the gauge of the real trains they are scaled from. All of these scales run on the same 9 mm (0.354 in) track gauge (N gauge). This means the track is a little too narrow for 1:148/1:150 but the difference is usually considered too small to matter. Strict 2 mm fine scale modellers use slightly wider and usually hand built track.
In Britain, some N scale models are built to "2 mm scale" for "2 mm to the foot" which calculates to a 1:152 proportion. Early N scale was also known as "OOO" or "Treble-O" in reference to O and OO and was also 1:152, though for an entirely different reason.
A number of modellers in the United Kingdom use 2 mm scale, a closer-to-scale standard than N scale. 2 mm scale is scaled at 2 mm to the foot (1:152) with a 9.42 mm (0.371 in) track gauge. Nearer to scale appearance is achieved by finer rail, flange and crossing dimensions than commercial N gauge (9 mm/0.354 in) components. A variation of the 2 mm standards is used by the FiNe group for 1:160 scale. It uses the same rail, flange and crossing dimensions as 2 mm (1:152) standards, but with a track gauge of 0.353 in (8.97 mm), and corresponding reduction in back-to-back. FiNe is dominated by European modellers.
In 1961 Lone Star introduced some of the very first (1:160) N scale models branded as Treble-0-Lectric (OOO) into the United Kingdom. The original die-cast metal models were push along and gauged to run on a die-cast trackwork having a gauge that was closer to 8 mm (0.315 in). Coupling was via a simple loop and pin arrangement. The novelty of the "Lone Star Locos" line was such that they even found their way to the United States and were sold in the toys area of major department stores like J.J. Newberry.
Electrified models followed soon after. The track gauge was widened to a nominal 9 mm (0.354 in) and rails were isolated with non-conductive ties (sleepers) for DC operation. Gearing between the motor and the axles at such a small scale was done by rubber bands, rather than the usual worm gear. A different coupling based on a shrunken OO scale coupling was fitted. The OOO couplings and specifications have long since been replaced by commercial N scale manufacturers.
Australian N scale
Australian Railways use several gauges across the states, although in most cases 9 mm gauge track is used. Some modellers have used Z gauge track for Nn3 models of Queensland Railways. N scale modelling in Australia has been a cottage-industry affair, with typically small runs of resin-based models being produced. Some etch-brass kits have also been released. In most cases the kits have been bodies designed to run on mechanisms or bogies available from overseas. Some very fine models are starting to emerge from various Australian manufacturers with many kits now available.
Manufacturers have started to engage Chinese manufacturers to produce very high quality wagons and locomotives. The Victorian producer Aust-N-Rail pioneered this approach, while in 2011 BadgerBits released Australia's first ready-to-run N gauge locomotive, a 48 class retailing for around A$240. A new manufacturer has arrived on the scene (November 2011) with Australia-N Railways using both Australian locally manufactured detail accessories and top end Chinese factories to produce their new locomotives and rolling stock. Australia-N Railways is releasing a new 81 Class designed from the rails up manufactured in China, which will be retailing at A$180. Other kits continue to be released using the more usual method of resin-based castings, and it is now possible to model railways in all states other than Tasmania, although the coverage is highly variable.
Japanese N scale
A 1/150 scale model of a Japanese railroad diorama.
Since former Japanese National Railway and other major private railways adopted track gauge of 1067 mm(3'6"), major Japanese N scale models adopted 1:150 with 9 mm gauge. But, in the case of Shinkansen which adopted 1435 mm of track gauge, so models of Shinkansen are scaled down to 1:160. A small number of modelers adopted a model scale of 1:120 with using 9 mm gauge tracks to represent the narrow gauge railway 3 ft 6 in (1,067 mm) gauge lines common in Japan. This is a different prototype gauge and scale to standard N scale with the narrower prototype gauge and called TT-gauge.