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Understanding Scales

Understanding Scales

  by Andy Slater

There seems to be quite a lot of confusion about scales. Particularly amongst those new to model making, but also among a good number of the 'old hands' who've simply worked around ever having to get to grips with the concept. It's really not difficult to understand and hopefully this article will clarify things.

In model making, when we refer a scale, we're usually talking about a ratio. Most models are NOT the same size as the real thing and the scale is a ratio, an expression of the relationship, between the size of the real thing and the size of the model.

Now I doubt that there's anybody out there who would have difficulty with what I meant if I referred to something as being 'quarter scale'. I'd simply mean that the model was one quarter of the size of the original such that something that was twelve feet tall in real life would be 3 feet tall as a model. Similarly if the real thing was 200mm long, the model would me 50mm long. It doesn't matter what unit you measure it in just so long as the measurement on the model is a quarter of the measurement on the real thing. Simple huh?

Now I also doubt that anybody will struggle if instead of saying 'quarter scale' I say '1/4 scale' as pretty much everybody is familiar with that way of writing a fraction? But if I say '1:4 scale' I can see that in some cases the mists will begin to descend. There's really no need though because it means the same thing. It's just a different way of writing it. In fact when you're expressing a ratio, which we are, its the correct way to write it.

So, now that we understand quarter scale (or 1/4 or 1:4 scale) how about if we take a leap forward and discuss 72nd scale (or 1/72 or 1:72)?

Hopefully nobody panicked because although you might not have understood it before, now that we've clarified just exactly what 1:4 scale means, hopefully it's now fairly clear that 1:72 scale means that something that's 72 units long in the real world will be 1 unit long as a model?

You'll probably recognise that 1:72 is a scale that's quite commonly used? Why not 1:71 or 1:73 though? Well the reason is that 72 inches is 6 feet so something which is 6 feet tall in the real world (like a man) will be 1 inch tall on a 1:72 scale model. This helps us to get a 'feel' for the scale because if you imagine a little 1 inch tall man interacting with your model you start to get feel for whether things are 'about right' without having to measure everything.

Upon investigation, you will find that most of the commonly used scales have some convenient measurement in the real world which equates to some other convenient measurement in the model world. (A little more information about this can be found in our facts and figures section.)

Hopefully that has now clarified things but before I finish there are a couple of things I should warn you about:

The first is that in railway modelling people use terms like N gauge and HO/OO gauge. This IS correct as it refers to the distance between the rails however you will also here people refer to N and HO/OO as if they are scales. This is not correct but happens because for each of the gauges there is usually a corresponding scale, often a 'nasty' number, and it's easier to refer to the gauge rather than the scale. (You can find a little more information about this in our facts and figures section.)

Another thing that happens in some genres of model making (Railway in particular) is that modellers refer to things as being in 2mm scale, 4mm scale, etc. These are abbreviations and if they said it in full they'd be saying '2mm to the foot' or '4mm to the foot'. What they are really saying therefore is that Xmm on their model equates to 1 foot in the real world.

This article is copyright (C) Andy Slater and is used here with permission
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