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Crain's Scale / Gauge Encyclopedia
1 Scale Name:  1:1 Scale          
  Scale Ratio:  1:1           
  Alternate Names: Full Scale Full Size          
       Scale       Model Track Gauge Error  Track
  Ser #           Gauge  Inches Ratio   In/ft  mm/ft       Inches           mm %  Used
  Correct Gauge:      
1 1  9 Foot Ga 108 1.0 12.0 305 108.0   2743   0  
1 2  100" Gauge 100 1.0 12.0 305 100.0   2540   0  
1 3  97" Gauge 97 1.0 12.0 305 97.0   2464   0  
1 4  8 Foot Ga 96 1.0 12.0 305 96.0   2438   0  
1 5  88" Gauge 88 1.0 12.0 305 88.0   2235   0  
1 6  86" Gauge 86 1.0 12.0 305 86.0   2184   0  
1 7  84.5" Ga 84.5 1.0 12.0 305 84.5   2146   0  
1 8  7 Foot Ga 84 1.0 12.0 305 84.0   2134   0  
1 9  6 Foot Ga 72 1.0 12.0 305 72.0   1829   0  
1 10  68.5" Ga 68.5 1.0 12.0 305 68.5   1740   0  
1 11  5.5 Ft Ga 66 1.0 12.0 305 66.0   1676   0  
1 12  65" Gauge 65 1.0 12.0 305 65.0   1651   0  
1 13  63" Gauge 63 1.0 12.0 305 63.0   1600   0  
1 14  5 Foot Ga 60 1.0 12.0 305 60.0   1524   0  
1 15  1440 mm Ga 56.7 1.0 12.0 305 56.7   1440   0  
1 16  1435 mm Ga 56.7 1.0 12.0 305 56.7   1435   0  
1 17  4ft 8.5in Ga 56.5 1.0 12.0 305 56.5   1435   0  
1 18  4 Foot Ga 48 1.0 12.0 305 48.0   1219   0  
1 19  1200 mm Ga 47.2 1.0 12.0 305 47.2   1200   0  
1 20  45.5" Ga 45.5 1.0 12.0 305 45.5   1156   0  
1 21  44.5" Ga 44.5 1.0 12.0 305 44.5   1130   0  
1 22  39.75" Ga 39.8 1.0 12.0 305 39.8   1010   0  
1 23  Meter Ga 39.4 1.0 12.0 305 39.4   1000   0  
1 24  950 mm Ga 37.4 1.0 12.0 305 37.4   950   0  
1 25  3 Foot Ga 36 1.0 12.0 305 36.0   914   0  
1 26  900 mm Ga 35.4 1.0 12.0 305 35.4   900   0  
1 27  891 mm Ga 35.1 1.0 12.0 305 35.1   891   0  
1 28  34" Gauge 34 1.0 12.0 305 34.0   864   0  
1 29  825 mm Ga 32.5 1.0 12.0 305 32.5   825   0  
1 30  800 mm Ga 31.5 1.0 12.0 305 31.5   800   0  
1 31  2.5 Ft Ga 30 1.0 12.0 305 30.0   762   0  
1 32  760 mm Ga 29.9 1.0 12.0 305 29.9   760   0  
1 33  750 mm Ga 29.5 1.0 12.0 305 29.5   750   0  
1 34  700 mm Ga 27.6 1.0 12.0 305 27.6   700   0  
1 35  27" Gauge 27 1.0 12.0 305 27.0   686   0  
1 36  620 mm Ga 24.4 1.0 12.0 305 24.4   620   0  
1 37  2 Foot Ga 24 1.0 12.0 305 24.0   610   0  
1 38  600 mm Ga 23.6 1.0 12.0 305 23.6   600   0  
1 39  23.5" Ga 23.5 1.0 12.0 305 23.5   597   0  
1 40  22" Ga 22 1.0 12.0 305 22.0   559   0  
1 41  21" Gauge 21 1.0 12.0 305 21.0   533   0  
1 42  18" Gauge 18 1.0 12.0 305 18.0   457   0  
1 43  15" Gauge 15 1.0 12.0 305 15.0   381   0  
1 44  9.5" Gauge 9.5 1.0 12.0 305 9.5   241   0  
       
For modeling purposes, many of these gauges are similar enough to be  
considered the same gauge. For example, 80 cm track is "close enough" to 2ft  
6in (30 in) to be considered the same gauge for modeling, especially in the
smaller scales. Therefore 80 cm gauge is not shown separately in subsequent  
tables. Similarly 60 cm and 24 inch gauge are treated as equals for modeling  
purposes.  42 inch gauge is also called Cape Gauge in South Africa.  
       
Crain's Scale / Gauge Encyclopedia
2 Scale Name:  6 Inch Scale        
  Scale Ratio:  1:2      
  Alternate Names:  1/2 Scale   Half Scale One Half Full Size    
     Represented    Scale       Model Track Gauge Error  Track
  Ser #     Gauge  Inches Ratio   In/ft  mm/ft       Inches           mm %  Used
  Correct Gauge:      
2 45  4ft 8.5in 56.5 2.0 6.0 152 28.25   718   0.0  
2 46  Meter 39.4 2.0 6.0 152 19.70   500   0.0  
2 47  3 Foot 36 2.0 6.0 152 18.00   457   0.0  
2 48  2.5 Foot 30 2.0 6.0 152 15.00   381   0.0  
2 49  2 Foot 24 2.0 6.0 152 12.00   305   0.0  
  Commonly Used Gauges    
2 50  29" Gauge 56.5 2.0 6.0 152 29.00   737   2.7  
2 51  28" Gauge 56.5 2.0 6.0 152 28.00   711   -0.9  
2 52  27" Gauge 56.5 2.0 6.0 152 27.00   686   -4.4  
2 53  19" Gauge 36 2.0 6.0 152 19.00   483   5.6  
2 54  18.5" Gauge 36 2.0 6.0 152 18.50   470   2.8  
2 55  6"n3 Gauge 36 2.0 6.0 152 18.00   457   0.0  
2 56  18" Gauge 36 2.0 6.0 152 18.00   457   0.0  
2 57  16" Gauge 36 2.0 6.0 152 16.00   406   -11.1  
2 58  6"n2.5 Ga 30 2.0 6.0 152 15.00   381   0.0  
2 59  15" Gauge 30 2.0 6.0 152 15.00   381   0.0  
2 60  14" Gauge 30 2.0 6.0 152 14.00   356   -6.7  
2 61  12 5/8" Ga 24 2.0 6.0 152 12.63   321   5.2  
2 62  12 1/4" Ga 24 2.0 6.0 152 12.25   311   2.1  
2 63  6"n2 Ga 24 2.0 6.0 152 12.00   305   0.0  
2 64  12" Gauge 24 2.0 6.0 152 12.00   305   0.0  
       
These scales are not often used by modelers, but some full or half size mockups are  
used to illustrate new products, or are set up in museums, advertisements, movies,  
or parades. A model manufacturer recently built a full size model of one of its G  
scale models, which itself was a model of a full size original. Thus, they created  
a 22.5 to 1 scale ratio.      
       
Crain's Scale / Gauge Encyclopedia
3 Scale Name:  5 Inch Scale 2.40      
  Scale Ratio:  1:2.4    
  Alternate Names:  None      
     Represented    Scale       Model Track Gauge Error  Track
  Ser #     Gauge  Inches Ratio   In/ft  mm/ft       Inches           mm %  Used
  Correct Gauge:              
3 65  4ft 8.5in 56.5 2.4 5.0 127 23.54   598   0.0  
3 66  Meter 39.4 2.4 5.0 127 16.42   417   0.0  
3 67  3 Foot 36 2.4 5.0 127 15.00   381   0.0  
3 68  2.5 Foot 30 2.4 5.0 127 12.50   318   0.0  
3 69  2 Foot 24 2.4 5.0 127 10.00   254   0.0  
  Commonly Used Gauges    
3 64  24" Gauge 56.5 2.4 5.0 127 24.00   610   1.9  
3 65  16" Gauge 36.0 2.4 5.0 127 16.00   406   6.7  
3 66  15" Gauge 36.0 2.4 5.0 127 15.00   381   0.0  
3 67  5"n3 Gauge 36.0 2.4 5.0 127 15.00   381   0.0  
3 68  14" Gauge 36.0 2.4 5.0 127 14.00   356   -6.7  
3 69  12 5/8" Ga 30.0 2.4 5.0 127 12.63   321   1.0  
3 70  5"n2.5 Ga 30.0 2.4 5.0 127 12.50   318   0.0  
3 71  12.5" Gauge 30.0 2.4 5.0 127 12.50   318   0.0  
3 72  12.5" Gauge 30.0 2.4 5.0 127 12.50   318   0.0  
3 73  12 1/4" Ga 30.0 2.4 5.0 127 12.25   311   -2.0  
3 74  12" Gauge 30.0 2.4 5.0 127 12.00   305   -4.0  
3 75  10 1/4" Ga 24.0 2.4 5.0 127 10.25   260   2.5  
3 76  5"n2 Gauge 24.0 2.4 5.0 127 10.00   254   0.0  
3 77  10" Gauge 24.0 2.4 5.0 127 10.00   254   0.0  
       
This is pretty rare stuff and not mentioned often.  
                         
Crain's Scale / Gauge Encyclopedia
4 Scale Name:  4 Inch Scale        
  Scale Ratio:  1:3    
  Alternate Names:  1/3 Scale   One-Third Scale One-Third Full Size
     Represented    Scale       Model Track Gauge Error  Track
  Ser #     Gauge  Inches Ratio   In/ft  mm/ft       Inches           mm %  Used
  Correct Gauge:              
4 78  4ft 8.5in 56.5 3.0 4.0 102 18.83   478   0.0  
4 79  Meter 39.4 3.0 4.0 102 13.13   334   0.0  
4 80  3 Foot 36 3.0 4.0 102 12.00   305   0.0  
4 81  2.5 Foot 30 3.0 4.0 102 10.00   254   0.0  
4 82  2 Foot 24 3.0 4.0 102 8.00   203   0.0  
  Commonly Used Gauges    
4 76  20" Gauge 56.5 3.0 4.0 102 20.00   508   6.2  
4 77  19" Gauge 56.5 3.0 4.0 102 19.00   483   0.9  
4 78  18-3/4" Ga 56.5 3.0 4.0 102 18.75   476   -0.4  
4 79  18 1/2" Ga 56.5 3.0 4.0 102 18.50   470   -1.8  
4 80  18" Gauge 56.5 3.0 4.0 102 18.00   457   -4.4  
4 81  12" Gauge 36.0 3.0 4.0 102 12.00   305   0.0  
4 82  4"n3 Gauge 36.0 3.0 4.0 102 12.00   305   0.0  
4 83  10 1/4" Gauge 30.0 3.0 4.0 102 10.25   260   2.5  
4 84  4"n2.5 Ga 30.0 3.0 4.0 102 10.00   254   0.0  
4 85  10" Gauge 30.0 3.0 4.0 102 10.00   254   0.0  
4 86  4"n2 Gauge 24.0 3.0 4.0 102 8.00   203   0.0  
4 87  8" Gauge 24.0 3.0 4.0 102 8.00   203   0.0  
4 88  7.5" Gauge 24.0 3.0 4.0 102 7.50   191   -6.3  
       
This size of model is expensive, weighs tons instead of pounds, and needs all  
outdoors to run in. Wealthy aristocrats and buinessmen have done it, as well  
as amusement parks.      
     
Crain's Scale / Gauge Encyclopedia
5 Scale Name:  3.4 Inch Scale        
  Scale Ratio:  1:3.5    
  Alternate Names:  None    
     Represented    Scale       Model Track Gauge Error  Track
  Ser #     Gauge  Inches Ratio   In/ft  mm/ft       Inches           mm %  Used
  Correct Gauge:      
5 89  4ft 8.5in 56.5 3.5 3.42 86.9 16.14   410   0.0  
5 90  Meter 39.4 3.5 3.42 86.9 11.26   286   0.0  
5 91  3 Foot 36 3.5 3.42 86.9 10.29   261   0.0  
5 92  2.5 Foot 30 3.5 3.42 86.9 8.57   218   0.0  
5 93  2 Foot 24 3.5 3.42 86.9 6.86   174   0.0  
  Commonly Used Gauges      
5 94  16" Gauge 56.5 3.5 3.42 86.9 16.00   406   -0.9  
5 95  10-1/4" Gauge 36 3.5 3.42 86.9 10.25   260   -0.3 Triang
       
This is a scale variant from Britain, rare elsewhere.  
       
Crain's Scale / Gauge Encyclopedia
6 Scale Name:  3 Inch Scale        
  Scale Ratio:  1:4    
  Alternate Names:  1/4 Scale       One-Quarter Scale One-Quarter Full Size
     Represented    Scale       Model Track Gauge Error  Track
  Ser #     Gauge  Inches Ratio   In/ft  mm/ft       Inches           mm %  Used
  Correct Gauge:      
6 96  4ft 8.5in 56.5 4.0 3.0 76.2 14.13   359   0.0  
6 97  Meter 39.4 4.0 3.0 76.2 9.85   250   0.0  
6 98  3 Foot 36 4.0 3.0 76.2 9.00   229   0.0  
6 99  2.5 Foot 30 4.0 3.0 76.2 7.50   191   0.0  
6 100  2 Foot 24 4.0 3.0 76.2 6.00   152   0.0  
  Commonly Used Gauges      
6 101  15" Gauge 56.5 4.0 3.0 76.2 15.00   381   6.2  
6 102  15-1/8" Ga 56.5 4.0 3.0 76.2 15.13   384   7.1  
6 103  14" Gauge 56.5 4.0 3.0 76.2 14.00   356   -0.9  
6 104  3"n3 Gauge 36 4.0 3.0 76.2 9.00   229   0.0  
6 105  9" Gauge 36 4.0 3.0 76.2 9.00   229   0.0  
6 106  3"n2.5 Ga 30 4.0 3.0 76.2 7.50   191   0.0  
6 107  7-1/2" Ga 30 4.0 3.0 76.2 7.50   191   0.0  
6 108  3"n2 Gauge 24 4.0 3.0 76.2 6.00   152   0.0  
6 109  6" Gauge 24 4.0 3.0 76.2 6.00   152   0.0  
       
Real people could afford this, but its more a passion than a hobby. Adults can  
ride and a few live steam trains could pull as many as a hundred people.  
       
Crain's Scale / Gauge Encyclopedia
7 Scale Name:  2.5 Inch Scale        
  Scale Ratio:  1:4.8    
  Alternate Names:  1/5 Scale   One-Fifth Scale One-Fifth Full Size
     Represented    Scale       Model Track Gauge Error  Track
  Ser #     Gauge  Inches Ratio   In/ft  mm/ft       Inches           mm %  Used
  Correct Gauge:      
7 110  4ft 8.5in 56.5 4.8 2.5 63.5 11.77   299   0.0  
7 111  Meter 39.4 4.8 2.5 63.5 8.21   208   0.0  
7 112  3 Foot 36 4.8 2.5 63.5 7.50   191   0.0  
7 113  2.5 Foot 30 4.8 2.5 63.5 6.25   159   0.0  
7 114  2 Foot 24 4.8 2.5 63.5 5.00   127   0.0  
7 115  15 Inch 15 4.8 2.5 63.5 3.13   79   0.0  
  Commonly Used Gauges    
7 116  12-5/8" Ga 56.5 4.8 2.5 63.5 12.68   322   7.7  
7 117  12" Gauge 56.5 4.8 2.5 63.5 12.00   305   1.9  
7 118  2.5"n3 Ga 36 4.8 2.5 63.5 7.50   191   0.0  
7 119  7-1/2" Ga 36 4.8 2.5 63.5 7.50   191   0.0  
7 120  7-1/4" Ga 36 4.8 2.5 63.5 7.25   184   -3.3  
7 121  2.5"n2 Ga 24 4.8 2.5 63.5 5.00   127   0.0 Ga.5
7 122  5" Gauge 24 4.8 2.5 63.5 5.00   127   0.0 Ga.5
7 123  Gauge 5 24 4.8 2.5 63.5 5.00   127   0.0 Ga.5
       
Still expensive, but this is a popular live steam scale.  
       
Crain's Scale / Gauge Encyclopedia
8 Scale Name:  VI Scale (European)    
  Scale Ratio:  1:5.5    
  Alternate Names:  "VI" = Roman Numeral Six Number Six Scale    
     Represented    Scale       Model Track Gauge Error  Track
  Ser #     Gauge  Inches Ratio   In/ft  mm/ft       Inches           mm %  Used
  Correct Gauge:      
8 124  4ft 8.5in 56.5 5.5 2.18 55.4 10.27   261   0.0  
8 125  Meter 39.4 5.5 2.18 55.4 7.16   182   0.0  
8 126  3 Foot 36 5.5 2.18 55.4 6.55   166   0.0  
8 127  2.5 Foot 30 5.5 2.18 55.4 5.45   139   0.0  
               
  Commonly Used Gauges              
8 128   10" Gauge 56.5 5.5 2.18 55.4 10.00   254   -2.7  
8 129  Gauge VI 39.4 5.5 2.18 55.4 7.16   182   0.0  
                       
A rare European scale from the early 1900's. One of six NEM standards for large scales
numbered I through VI (Roman numerals).
   
Crain's Scale / Gauge Encyclopedia
9 Scale Name:  2 Inch Scale        
  Scale Ratio:  1:6    
  Alternate Names:  1/6 Scale   One-Sixth Scale One-Sixth Full Size
     Represented    Scale       Model Track Gauge Error  Track
  Ser #     Gauge  Inches Ratio   In/ft  mm/ft       Inches           mm %  Used
  Correct Gauge:      
9 130  4ft 8.5in 56.5 6 2.0 50.8 9.42   239   0.0  
9 131  Meter 39.4 6 2.0 50.8 6.57   167   0.0  
9 132  3 Foot 36 6 2.0 50.8 6.00   152   0.0  
9 133  2.5 Foot 30 6 2.0 50.8 5.00   127   0.0  
9 134  2 Foot 24 6 2.0 50.8 4.00   102   0.0  
  Commonly Used Gauges    
9 135  10-1/2" Ga