Steve's Scale and Gauge Charts

 

Definitions

Scale
The ratio between the size of the models and the size of the prototype. This can be expressed either as a ratio or as so many millimetres per foot (or fractions of an inch per foot for American models).
 
Gauge
The distance between the rails. Standard gauge is 1435mm (4 foot 8-1/2 inches) or the equivalent distance scaled down on the model. Anything narrower than this is called narrow gauge and anything wider is called broad gauge. In most cases the actual gauge used on the model varies slightly from the correct distance when scaled down from the prototype. Refer to the prototype gauge chart following for actual gauges used in various parts of the world.
 
Scale Name
Each popular scale is given a name which indicates, not only the scale to which the model railway / railroad model is being built, but also gives an indication of the track gauge used. The actual scale and gauge associated with a given name may vary depending on the prototype being modelled. In the case of narrow gauge the names also usually give an indication of the gauge of the prototype being modelled.
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Prototype Gauge

The following chart is a representative list of some of the various gauges used by prototype railways around the world.

 MetricImperialCountries/Regions
broad2140mm7' 0-1/4" Britain (GWR until 1892)
 1676mm5' 6" Spain, Portugal, India, Chile
 1600mm5' 3" Ireland (CIE, GNR, NCC), Australia (Vic, SA), Brazil
 1524mm5' 0" Russia, Finland
standard1435mm4' 8-1/2" Australia, Austria, Belgium, Bolivia, Bulgaria, China, Czechoslovakia, Canada, Denmark, Egypt, France, Germany, Britain, Holland, Hungary, Italy, Japan, Yugoslavia, Mongolia, Norway, Poland, Peru, Rumania, Sweden, Switzerland, Turkey, USA
narrow1067mm3' 6" Australia (WA, SA, Qld, NT, Tas), New Zealand, South Africa, Japan, Spain, East Africa, Canada (CNR, Newfoundland), Ecuador, Java
 1000mm3' 3-3/8" Germany, Switzerland, Spain, India, Burma, Kenya, Malaysia, Thailand, Uganda, Chile
 950mm3' 1-1/2" Italy (Dolomites, Sardinia)
 914mm3' 0" Isle of Man, Ireland (County Donegal), USA (D&RGW), Canada (WP&Y)
 800mm2' 7-1/2" Wales (Snowdon Mtn Rly), Switzerland (Wengernalp Rly)
 760mm2' 6" Australia (Vic), Wales (Welshpool&Llanfair), Austria (Zillertalbahn), India
 750mm2' 5-1/2" Germany, Egypt, Indonesia
 686mm2' 3" Wales (Tal y Llyn Rly)
 610mm2' 0" Australia (Qld, Tas), Fiji
 600mm1' 11-5/8" Wales (Festiniog, Vale of Rheidol), Greece
 381mm1' 3" Romney Hythe & Dymchurch and Ravenglass & Eskdale (UK), Driving Creek (NZ)

 

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Standard Gauge

The following are some of the scales that are (or have been) used by modellers to model standard gauge railways. The gauges used vary in the accuracy of their representation of true standard gauge. The more common and popular scales are shown in bold.

NameScalemm/ftgauge (mm) 
41:154/5in3in 
31:182/3in2-1/2in 
21:241/2in2in 
11:30.51045 British
11:329.545 European
11:323/8in1-3/4in American
O1:43.5732 
Scale 71:43.5733 
O1:456.832 European
O171:4517/64in1-1/4in American
O1:481/4in1-1/4in American
Q1:481/4in1-3/16in American
Proto 481:481/4in29.89 American
S or H11:643/16in7/8in 
OO1:76.2419 American
P4/S41:76.2418.83 
EEM1:76.2418.8 
EMF1:76.2418.2 
EM1:76.2418 
OO1:76.2416.5 British
HO1:87.13.516.5 
QO1:961/8in3/5in 
TT1:100313 European
TT31:101.6312 British
Scale 31:102314.12 
TT1:1202.5412 
HOO1:145210 
N1:1482-1/169 British
OOO1:15229.5 
N1:1502.0329Japanese
N1:1601.99 
K1:1741.758 
QOO1:1741.757.62 
Z1:2201.46.5 
X1:304.814.5 
T1:4500.683 

 

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Narrow Gauge

The following are some of the scales that are (or have been) used by modellers to model narrow gauge railways. The more common and popular scales are shown in bold.

NameScalemm/ftgauge (mm)gauge prototype 
SM451:191645  approx. 3 on 1 track
SM321:191632two foot approx. 3 on O track
2n31:241345  
2m1:22.513.745metre 
G1:221445metre LGB - approx. 2 on O track
G1:291445  (some models)
Gn151:221416.515 inch 
Om1:48722.5metre 
On31:481/4in19three foot O on American OO track
On2-1/2 or On301:481/4in16.5two foot six O on OO track
Oe1:481/4in16.5750mm O on OO track
O16.51:43.5716.5two foot O on OO track
On21:48714two foot 
Sn3-1/21:643/16in16.5three foot six 
Sn31:643/16in14three foot 
Sn21:643/16in9two foot 
OOn3 or OO121:76.2412three foot OO on TT3 track
OO91:76.249  British OO on N track
OO61:76.246eighteen inch British OO on Z track
HOm1:87.13.512metre HO on TT track
HOn31:87.13.510.5three foot 
HOe1:87.13.59750mm 
HOn2-1/2 or HO301:87.13.59two foot six HO on N track
HOn21:87.13.56two foot HO on Z track
TTn31:101.139three foot TT3 on N track
Nm or Nn31:1601.96.5  N on Z track

 

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