FAQ 2. What is the difference between Gauge and Scale?

GAUGE and SCALE in relation to Model Railways are two very different things. As with real-life Railways, GAUGE measures the distance between the rails. Hence in Australia we have Broad Gauge, Standard Gauge or Narrow Gauge Railways.

SCALE, on the other hand, expresses the size of the model in relation to its real-life prototype. SCALE is usually expressed as a ratio. For example, HO SCALE is 1:87.  This means an HO model will be one eighty-seventh the size of the real locomotive or carriage. OO Scale is 1:76. This means an OO Model will be one seventy-sixth the size of the real locomotive or carriage.

The important thing to note is that different SCALE trains will can run on the same GAUGE track.  (This will often represent trains running on Narrow Gauge, for example). The most common application of this is that HO Scale and OO Scale Trains both run on the same Gauge Track. 

For those who would like a little more detail, the following lists the most common Model Railway Gauges in increasing order of size:

N Gauge
1:148 scale which is 2mm to 1 foot
Runs on 9mm Gauge Track
Virtually half the size of OO

HO Gauge
1:87 scale which is 3.5mm to 1 foot
Runs on 16.5mm Gauge Track
This is the same Gauge Track as OO

OO Gauge
1:76 scale which is 4mm to 1 foot
Runs on 16.5mm Gauge Track
OO is the most common Gauge Track

O Gauge
1:43.5 scale which is 7mm to 1foot
Runs on 32mm Gauge Track

G Gauge
A variety of scales run on G Gauge Track which is 45mm