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Table 1 Model Train Scales

Table 1 below defines the various more common model train scales and gauges:

N Scale (ratio of model dimension to actual size) 1:148 to 1:160 Varies with manufacturer and country
     
N-Scale gauge  (distance between track rails) 9 mm (0.354 in)  
     
N-Scale Minimum diameter 17 in  
     
HO Scale (ratio of model dimension to actual size) 1:87  

     
HO -Scale gauge  (distance between track rails) 16.5 mm (0.650 in)  
     
HO- scale minimum diameter 30 in  
     
HOn3-1/2 Scale (ratio of model dimension to actual size) 1:87 Used for narrow gauge railroads
     
HOn3-1/2 -Scale gauge  (distance 12 mm (0.472 in) 3 ½ scale feet between rails
     
HOn 3-1/2- scale minimum diameter 30 in  
     
O Scale (ratio of model dimension to actual size) 1:48  
     
O-Scale gauge  (distance between track rails) 30 mm (1.181 in) (at 1:48 scale),  
     
O- scale minimum diameter 31 in  
     
O -27 Scale (ratio of model dimension to actual size) 1:48  
     
O-27 Scale gauge  (distance between track rails) 30 mm (1.181 in) (at 1:48 scale),  
     
O- 27 scale minimum diameter 27 in  
     
     
S-Scale (ratio of model dimension to actual size) 1:64  
     
S-Scale gauge  (distance between track rails) 22.42 mm (0.883 in)  
     
S- scale minimum diameter 40 in  
     
TT-Scale (ratio of model dimension to actual size) 1:120  
     
TT-Scale gauge  (distance between track rails) 12 mm (0.472 in)  
     
TT- scale minimum diameter 21 in  
     
G-Scale (ratio of model dimension to actual size) 1:22.5  
     
G-Scale gauge  (distance between track rails) 1.77 in  
     
G- scale minimum diameter 5 feet  

 

     
Z-Scale (ratio of model dimension to actual size) 1:220  
     
Z-Scale gauge  (distance between track rails) 6.5 mm(0.256 in)  
     
Z- scale minimum diameter 11.5 in  
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