Should it be:

1KG or 1 KG?

1M or 1 M?

1PM or 1 PM?

1GB or 1 GB?

1Kmph or 1 Kmph?

1Kbps or 1 Kbps?

or anything else?

  • What does your research show, and what aspects of this does it not explain? Jul 28, 2017 at 13:39
  • @MaxWilliams in Grammarly is says use space for 1PM but for other quantities it doesn't give any suggestions. Also I have seen music websites using 128Kbps and also 128 Kbps to show bit rate of songs. I am confused. Jul 28, 2017 at 13:43
  • thanks, I just wanted to make sure you weren't one of the people who come here before they go to the dictionary :) I've written an answer which might not actually help very much... Jul 28, 2017 at 14:03
  • Mind undoing the down vote then? Jul 28, 2017 at 14:05
  • That wasn't me. Jul 28, 2017 at 14:05

1 Answer 1


The correct usage is to have a space. Apart from that, there are no hard and fast rules. They are more commonly lower case, but not always.

Even for any given unit abbreviation there may be a lot of different variations. For example, "Kilometers per hour" is complex enough to have it's own wikipedia page. That page lists 18 different abbreviations!

So, you need to proceed on a case-by-case basis, for each abbreviation.

Within some abbreviations, a change in capitalisation can mean a different thing: for example, in the computing world, "B" often stands for "byte" and "b" for "bit".

That leads me on to another complicated one, "GB", which at face value can mean "gigabytes" (not to be confused with GB for Great Britain, in the Olympics). But, the definition of what a "gigabyte" is has been the subject of some controversy over the years: is it a billion bytes, a million kilobytes (each of which is 1024 bytes, not a thousand bytes), 2^30 (1024*1024*1024) bytes, etc? This has lead to the new word "Gibibytes", which has not gained widespread adoption and has if anything only added to the confusion.

So, as you can see, abbreviations are complicated and there are not many standard rules. As I said in the first sentence, they should generally be seperated from the preceding number by a space, but they can be subect to a sort of compound-word process, where the number and the unit join together to make a sort of "label": this is what we see with "128kbps" for example: 128kbps is really a sort of adjective applied to a network or encoding process, telling us its maximum theoretical bandwidth (which it will probably never actually reach in practise). So it's like a label rather than a measurement.

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