On the left you see a set of scale rules covering all scales. Scale is the difference between the size of the ‘real’ thing and the size you want to model in.
For example, if you want to make a model which is half the size of the real one it is to a scale of 1:2 (1/2); if you want it to be to a scale 50 times smaller than the real thing it is 1:50 (1/50).
In the picture on the right you see a person who is to a scale of 1:1 (full size) but the train they are sitting on is around 1:15 (1/15).
Therefore; the larger the item you want to model the bigger the difference in the ratio between real and model sizes. That is why models of trains are around 1:76 and the scale of ships is around 1:700.
What gauge shall I model in ?
As you can see on left model trains come in different sizes and this is where scale and gauge come together. The ones shown are from the Bachmann range and are available as follows:
‘O’ gauge which is 1:43
’00’ gauge which is 1:76
‘N’ gauge which is 1:148