Model Train Scale / Gauge quick guide

 Scale Ratio Gauge (Track rails spaced apart) T 1:450 3 mm Z 1:220 6.5 mm (0.256 in) N 1:160 9 mm (0.354 in) h0 (HO) 1:87 16.5 mm (0.650 in h0n3 1:87 9 mm (Narrow Gauge) 00 (OO) 1:76 16.5 mm (0.650 in) S 1:64 22 mm 0 (O) 1:43.5 (1:45) 32 mm 1 1:32 45 mm G 1:22.5 45 mm (Narrow Gauge)

Below is a first "european" comparison chart. It gives most combinations available.

Sample 1: When modelling standard gauge prototype in scale 1:87, the scale name would be h0 (half zero or commonly HO) and the gauge 16,5mm.

Sample 2: When modelling meter gauge prototype in scale 1:22,5, the scale name would be IIm (2m) and the gauge 45mm.

Sample 3: If one wanted to model South African mainline prototype in 1:87 one would use TT track, although the sleepers wouldn?t be spaced correctly!

 prototype gauge Scale 1:220 1:160 1:120 1:87 1:64 1:45 1:32 1:22,5 1:16 1:11 1:8 1:5,5 1250~1700 Z N TT h0 S 0 I II III V VII X 850 < 1250 Zm Nm TTm h0m Sm 0m Im IIm IIIm Vm VIIm Xm 650 < 850 Ne TTe h0e Se 0e Ie IIe IIIe Ve VIIe Xe 400 < 650 TTi h0i Si 0i Ii IIi IIIi Vi VIIi Xi in mm 4,5 6,5 9 12 16,5 22,5 32 45 64 89 127 184 260 in inch 1 3/4 2 1/2 3 1/2 5 7 1/4 10 1/4

Model gauges

note 1: From I scale up arabic numerals are common
note 2: 0 scale used to be 1:43,5 and in some countries still is
note 3: For the larger scales the inch description is more common

Used indexes with scale name:

(European)

m = meter gauge
e = narrow gauge

(American)

n = narrow gauge
nX = narrow gauge plus indication of prototype gauge in feet, i.e. n2 or n3.

So in 1:87 scale meter gauge would be h0m and 3 feet gauge would be h0n3

For all intents and purposes it is the same.

Then to add to the confusion, the islanders have to be different of course. They use 1:76 (00) and 1:148 instead of the normal 1:87 and 1:160.

It is difficult to pick this up in a model as the prototypical loading gauge is smaller than the continental or the American one.

And they sometimes indicate scale in mm per foot as well:

3,5mm scale would be 1:87 (h0)
4mm scale would be 1:76 (00)
7mm scale would be 1:43,5 (0)
2mm scale would be 1:152

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