Gauge/Scale Sizes
| Name | Gauge | Scale | Notes |
|---|---|---|---|
| Z | 6.5mm | 1:220 | |
| Nn3 | 6.5mm | 1:150ish | Scale may vary 1:148, 1:152 or 1:160 |
| N | 9mm | 1:160 | Standard everywhere except UK |
| UK N | 9mm | 1:148 | 2mm:1ft scale |
| 2FS | 9.42mm | 1:152 | 2mm:1ft (finescale) |
| 009 | 9mm | 1:76 | UK Narrow gauge |
| TT | 12mm | 1:120 | |
| TT3 | 12mm | 1:100 | Triang 3mm |
| 3mm | 14.2mm | 1:102 | |
| HOe | 9mm | 1:87 | European 750/760mm gauge |
| HOm | 12mm | 1:87 | HO metric gauge |
| HOn30 | 9mm | 1:87 | US 30in gauge at 1:87 scale |
| HOn3 | 10.5mm | 1:87 | US 3ft gauge in HO |
| HO | 16.5mm | 1:87 | |
| OO | 16.5mm | 1:76 | |
| EM | 18mm | 1:76 | |
| P4 | 18.83mm | 1:76 | finescale 4mm:1ft |
| On3 | 22mm | 1:48 | US 3ft gauge in O |
| S | 22.2mm | 1:64 | 4.8mm:1ft scale (UK) |
| O | 32mm | 1:43.5 | 7mm:1ft - 1:45 used in Europe and 1:48 used in USA |
| ScaleSeven | 32.95mm | 1:43.5 | finescale 7mm:1ft |
| O:16.5 | 16.5mm | 1:43 | 7mm:1ft narrow gauge |
| On30 | 16.5mm | 1:48 | US 30in gauge in 1/4in scale |
| Gauge1 | 45mm | 1:32 | |
| G-scale | 45mm | 1:22.5 | garden scale |
| Gauge2 | 50.4mm | 1:28 | 2in gauge |
| Gauge1 | 63.5mm | 1:22 | 2-1/2in gauge |
Thanks to Digitrax Inc of Norcross, Georgia USA for most of this information.
