MICRO LAYOUTS FOR MODEL RAILROADS

Carl's Guide to Scales and Gauges
Commonly Used for Small Layouts

I've received a number of questions recently about the scales and gauges
used in model railroading around the world. So I'm repeating here a table
that first appeared in my book, Creating Micro Layouts. I've added a few
more scale/gauge combinations and welcome your additional suggestions.

Gauge
 Name
 Scale
 Proto-
type
 Propor-
tion
 Comments
1.75in (45mm)
 7/8
 7/8in = 1ft
 24 in
 1:13.7
 Very large trains; for scratchbuilders

Fn3
 15mm = 1ft
 36 in
 1:20.3
 Variant of G, mainly Bachmann

Gm
 45mm = 1m
 1000mm
 1:22.5
 Metre gauge - LGB and others

Hn42
 1/2in = 1 ft
 42in
 1:24
 Mainly in New Zealand/Australia

1
 3/8in = 1ft
 56.5in
 1:32
 Standard gauge - Märklin and others
1.25in (32mm)
 7/8
 7/8in = 1ft
 18in
 1:13.7
 For scratchbuilders

SM32
 16mm = 1ft
 24in
 1:19
 Mainly in garden railways

Hn30
 1/2in = 1 ft
 30in
 1:24
 For scratchbuilders

1m
 3/8in = 1ft
 1000mm
 1:32
 European metre gauge

9 Mil
 9mm = 1 ft
 42in
 1:32
 Used mainly in NZ

O (U.K.)
 7mm = 1ft
 56.5in
 1:43.5
 Standard gauge - many mfgrs

O(Europe)
1435mm 1:45 Standard (normal) gauge - many mfgrs

O (U.S.) 1/4in = 1ft 56.5in 1:48 Standard gauge - many mfgrs
7/8in
S
 3/16in = 1ft
 56..5in
 1:64
 Standard gauge
3/4in
 1n2
 3/8in = 1ft
 24in
 1:32
 For scratchbuilders

On3
 1/4in = 1ft
 36in
 1:48
 Primarily in U.S.
16.5mm
 Gn15
 13.5mm = 1ft
 15in
 1:22.5
 A few mfgrs

Hn18
 1/2in = 1ft
 18in
 1:24
 A few mfgrs

1n21
 3/8in = 1ft
 20-22in
 1:32
 For scratchbuilders

1/36 8.5mm = 1ft 24in 1:36 For scratchbuilders

O16.5
 7mm = 1ft
 ~28in
 1:43.5
 Popular in U.K.

On30 1/4in = 1ft 30in 1:48 Popular - Bachmann and others

OO
 4mm = 1ft
 56.5in
 1:76
 U.K. Standard gauge, very popular

HO 3.5mm = 1ft 56.5in 1:87 Standard gauge, very popular
14mm
 On2, O14
 7mm = 1ft
 24in
 1:43.5
 Mainly for scratchbuilders - Roy C. Link
12mm OOn3
 4mm = 1ft
 36in
 1:76
 U.K. three-foot gauge

HOm
 3.5mm = 1 ft
 1000mm
 1:87
 European metre gauge

TT
 2.5mm = 1ft
 1435mm
 1:120
 Standard (normal) gauge
10.5mm
 Sn2
 3/16in = 1ft
 24in
 1:64
 Mainly in U.S.

HOn3
 3.5mm = 1ft
 36in
 1:87
 Popular in U.S.
9mm
 O9
 7mm = 1ft
 15in
 1:43.5
 Some U.K. mfgrs - Avalon and others

On18
 1/4in = 1ft
 18in
 1:48
 A few mfgrs

Sn2
 3/16in = 1ft
 24in
 1:64
 Popular in U.S.

OO9
 4mm = 1ft
 27in
 1:76
 Popular in U.K.

HOn30
 3.5mm = 1ft
 30in
 1:87
 Popular, a number of mfgrs

HOe
 3.5mm = 1ft
 650-850mm
 1:87
 Popular in Europe

NZ120
 2.5mm = 1ft
 42in
 1:120
 New Zealand TTn42

N
 .075in = 1ft
 56.5in
 1:160
 Standard gauge, very popular
6.5mm HOn2,
HOi
 3.5mm = 1ft
 22-24in, 400-650mm
 1:87
 For scratchbuilders

Nn3, Nm
 .075in = 1ft
 36in, 1m
 1:160
 U.S. three-foot, Europe metre gauge

Z
56.5in
 1:220
 Standard gauge - Märklin and other

Revised and Expanded 25 June 2006


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