# Terminology for expressing the scale of a measurement system

I'm looking for the most applicable terminology for defining the scale of measurement units in a particular system.

For example, for a distance, in 'metric', the 'small' scale could be 'm' and the 'big' scale could be 'km'. In 'imperial', the 'small' scale could be 'feet' and the 'big' scale could be 'miles'.

Similarly with a speed, the 'small' and 'big' scales could be 'm/s' and 'km/h' respectively for the metric system, and 'ft/s' and 'mph' respectively for the imperial system.

Throughout this post I've referred to a 'small' and 'big' 'scale'. Are there better terms I could use?

• I would be tempted to use comparatives or superlatives, e.g. `m/s is the smaller scale, and km/h is the largest scale.` I also don't know if a specific term exists for what you're trying to describe though.
– Lou
Jun 2, 2014 at 12:52
• I highly doubt there is a system of nomenclature for this, since the very concept you’re trying to describe just doesn’t work very well. Measurement systems are all highly complex because of how they interact. You can barely even say that one type of measurement is ‘smaller’ or ‘larger’ than just one other (is m/h smaller or larger than km/s, for example?), much less in absolute terms. Jun 2, 2014 at 14:03

You could use the prefixes micro- and macro- to describe the two extremes.

You may have to define your use of them in your writing. Otherwise, they may be interpreted as micron scale vs kilometer scale.

• Thanks, I ended up sticking with 'small' and 'big' as I think 'micro' and 'macro' are quite loaded terms and I just needed something to indicate the scale rather than explicitly state in. In this case, the vagueness of the terms works in my favour. Jun 2, 2014 at 19:21

could it be "base unit"? and then "multiples" or "derived".

What you describe is perfectly clear, but I think there's no terminology for that.

So, meters (feet) is the base unit of the metric (imperial) length system; and kilometers, centimeters (miles, yards) are multiples in the metric (imperial) system.

Hope it helps...

• note that "base unit" isn't always the 'small' unit. The base SI unit of mass is the kilogram (defined as the mass of a particular metal object in France), while the gram is a derived unit defined as 0.001 kilogram.
– bdsl
Jun 2, 2014 at 12:21
• right. BTW I hear they're trying to redefine kg as a photon energy count. Jun 2, 2014 at 12:25

The scale is highly contextual. The definition of big and small will depend on what you're measuring. The phrase regime is often used to indicate the context.

For example, when measuring the size of people you'd use meters or centimeters but when measuring the size of atoms you'd use angstroms or nanometers.

The best way to approach this is to use "`PREFIX`-scale" where `PREFIX` corresponds to the appropriate power of ten for your application. This is why we have the prefixes.

For example, atom sizes are nano-scale, sizes of cells are micro-scale and so on. X-ray frequencies correspond to peta-scale to exa-scale.

Exceptions to this are Planck scale which describes the regime where quantum effects of gravity are significant. The scale corresponds to time, mass and length units at megnitudes of 10-44 s, 10-8 kg and 10-35 m.