Model Railroading Scales - What Do the Letters Mean?

     Model railroading is fascinating and has been dubbed by many as the “World’s Greatest Hobby”.   It is very versatile and incorporates many learning opportunities and is so much fun for all ages. It includes creativity with sculpturing, painting, airbrushing, decorating and landscaping, and encourages scientific exploration of electronics, physics, mechanics, engineering and architecture, all combined with humour, friendship, family activities, social interaction, and the great sense of accomplishment.

Many people who visit us ask if there is significance to the letter referral to different size trains; N, HO, O, G, etc.  The answer is YES!!  We've compiled a list of all the scales and why they were named with that letter designation.

Please leave a comment after you've read this post and let us know what your thoughts on gauge and scale are and if this was helpful to you or not.

T - Ø 1:450 (referred to as 'Tiny' or 'Tokyo' as it was introduced at the Tokyo Toy Show in 2006)

ZZ - Ø 1:300 (Until the 2006 announcement of T scale, ZZ scale was the smallest commercially available scale for model railroads)

Z - Ø  1:220 (with all the letters identifying gauges Z became the smallest so they used the last letter in the alphabet)

N - Ø 1:160 (track gauge is 9mm, the N stands for Nine mm)

2mm - Ø 1:152 (similar in size to the slightly larger British N scale at 1:148 and the slightly smaller European/American N scale at 1:160; it predates both versions of N scale)

TT - Ø 1:120 (referred to as Table Top as it fit so easily on coffee tables)

3mm - Ø 1:101 (also known as 3 mm finescale, is a model railway scale of 3 mm: 1ft used for British prototypes. Introduced as British TT gauge)

OO- Ø 1:76 (Runs on HO track and is the British counterpart)

HOn3 - Ø 1:87 (The "n" in HOn3 stands for 'narrow gauge', HOn3 is still HO scale)

HO - Ø 1:87 (Half O or ‘aitch oh’)

S - Ø 1:64 (First named Standard Gauge then to represent that Scale that was half of 1 gauge which was built to 1:32 scale)

On3 - Ø 1:48 (is narrow gauge O scale)

O - Ø 1:48 (was referred as zero (or 0h) gauge)

G - Ø  1:22.5 ( G stands for Garden)

Live Steam - Ø  1:2, 1:4 or 1:3 scale  (Ridable, large-scale, powered by steam)

Gauge refers to the width of the track, measured between the railheads.  Different from scale, which is proportion to life-size.

At present, Chinook & Hobby West carries three Scales of Model Trains for Sale:  O scale, HO Scale, and N scale.  This article was researched through Atlas, Kato, NMRA and Bachmann.