| In the early part of the 20th century, model train | | | | Gauge 2 with a 1:29 ratio and a 2 inch (50.4 - 50.8 |
| maker Marklin tried to create a standard for | | | | mm) gaugeo 1 gauge 3/8 inch scale with a 1:32 |
| gauge of model train track. This met with some | | | | ratio and a 1.78 inch (45 mm) gaugeo O scale |
| success, but new scales came out after the | | | | with ratios of 1:43.5, 1:45, and 1:48 and a 1.78 inch |
| standards were put in place. Some of those | | | | (45 mm) gaugeo Proto:48 with a 1:48 ratio and a |
| scales were never addressed as to standard. | | | | 1.18 inch (29.90 mm) gaugeo Z0 with a 1:60 ratio |
| The larger models, which have been built to carry | | | | and a .94 inch (24 mm) gaugeo EM gauge with a |
| people, have few standards as they are usually | | | | 1:76.2 ratio and a .72 inch (18.2 mm) gaugeo P4 |
| made-to-order. A grand scale train, which is a | | | | gauge with a 1:76.2 ratio and a .74 inch (18.83 |
| ¼ scale or larger, has a gauge of 10 inches | | | | mm) gaugeo Proto:87 with a 1:87 ratio and a .65 |
| (254 mm) or more. The larger live steam trains | | | | inch (6.5 mm) gaugeo Hon3-1/2 scale (H0m |
| have a ratio of 1:8, and their gauge will vary from | | | | European) with a 1:87 ratio and a .48 inch (12.25 |
| 7.25 and 7.48 inches (184 - 190 mm). The smaller | | | | mm) gaugeo H0e with a 1:87 ratio and a .35 inch |
| live steam trains are scaled at 1 inch per foot. | | | | (9 mm) gaugeo 3 mm scale (TT-3) with a 1:101.1 |
| Their gauge ranges from 4.76 to 5 inches (121 - | | | | ratio and either a .47 or a .56 inch (12 - 14.2 mm) |
| 127 mm). The SE, or otherwise called 7/8 inch, | | | | gaugeo 2 mm scale with a 1:152 ratio and a .37 |
| scale has a ratio of 1:13.71 and a gauge of 1.5 | | | | inch (9.42 mm) gauge. |
| inches (45 mm). | | | | The more common model train scales are, from |
| The remaining models that can be ridden are:o | | | | the largest to the smallest:o G scale with a ratio |
| Live steam with a 1:16 ratio and 3.5 inch (89 mm) | | | | of 1:22.5 and a 1.78 inch (45 mm) gaugeo S gauge |
| gaugeo Gauge 3 with a 1:22.5 ratio and 2.52 inch | | | | with a ratio of 1:64 and a .88 inch (22.42 mm) |
| (64 mm) gaugeo Live steam with 1:24 ratio and | | | | gaugeo OO gauge with a ratio of 1:76.2 and a .65 |
| 2.48 inch (63 mm) gauge | | | | inch (16.5 mm) gaugeo HO scale with a ratio of |
| Standard Gauge (Lionel Trains) was also called | | | | 1:87 and a .65 inch (16.5 mm) gaugeo TT scale |
| Wide Gauge. These had a ratio of either 1:26.59 | | | | with a ratio of 1:120 and a .47 inch (12 mm) |
| or 1:28.25, and ran on a 2 1/4 inch (53.975 mm) | | | | gaugeo N scale with a ratio of 1:148(UK), |
| track. | | | | 1:150(Japan), or 1:160(Germany) and a .35 inch (9 |
| Other lesser known models include:o 16 mm scale | | | | mm) gaugeo Z scale with a ratio of 1:220 and a 1 |
| with a 1:19.05 ratio and a 1 1/4 inch (32 mm) | | | | 4 inch (6.5 mm) gaugeo ZZ scale with a ratio of |
| gaugeo Fn3 scale with a 1:20.3 ratio and a 1.78 | | | | 1:300 and a .19 inch (4.8 mm) gaugeo T scale with |
| inch (45 mm) gaugeo 1/2 inch scale with a 1:24 | | | | a ratio of 1:450 and a 1/8 inch (3 mm) gauge |
| ratio and a 1.78 inch (45 mm) gaugeo Gauge 2 | | | | As you can see, model train track varies a great |
| with a 1:29 ratio and a 1.78 inch (45 mm) gaugeo | | | | deal, even among trains of the same scale. |