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I'm working on a lighting product catalogue with products from many overseas suppliers. In regards to colour temperature, some of them put a space character before Kelvin symbol, some not:

4000K, 5600K

or

4000 K, 5600 K

Is there any official recommendation here?

Edit: It was suggested that this question is a duplicate of similar question related to computer symbols, suggesting it depends on style, and I happily agreed and considered that question as answered. However just now I've just found that there actually is an official recommendation related to SI unit symbols. Which makes the situation different than with units of computer storage.

ellockie
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  • This is arguably off topic but I wouldn't flag it as such (though we've had enough related questions that the SI handbook could become general reference). – Chris H Aug 14 '15 at 19:12
  • possible duplicate of Should thin spaces be used between numerals and units – Edwin Ashworth Aug 14 '15 at 19:35
  • 4000°K, 5600°K etc. – Wayfaring Stranger Aug 15 '15 at 00:10
  • @EdwinAshworth It seems that for certain units, like official SI units, there are some official standards, but for other not. The linked question was in my opinion a more generic question, about any units, however it has one relevant answer. It seems that some units, like computer memory units, are OK with or without separating space. – ellockie Aug 16 '15 at 01:46
  • @WayfaringStranger The degree sign shouldn't be used with Kelvins. – ellockie Aug 16 '15 at 01:47
  • ellockie:Looks too much like a rate constant when written without it. – Wayfaring Stranger Aug 16 '15 at 01:53
  • @WayfaringStranger Perhaps :) But definitely Kelvins should go without the degree symbol. Also when talking about temp. in Kelvins people don't usually mention the word "degree". – ellockie Aug 16 '15 at 02:20
  • I'm talking handwriting, which I realize is very old fashioned, but k and K can be hard to distinguish when jotting down a note. The little circle clarifies; whereas trying to do kinetics in LaTeX is just an exercise in frustration. – Wayfaring Stranger Aug 16 '15 at 03:00
  • SI pronouncements are not binding in English per se. I remember the ridiculous situation where pupils would lose a mark for spelling sulphur 'sulphur' in science, but would lose a mark for spelling it 'sulfur' in English. – Edwin Ashworth Aug 16 '15 at 08:01
  • @Wayfaring Stranger At least in a scientific register, the degree is neither pronounced nor indicated. 4000 K, 5600 K etc. – Edwin Ashworth Aug 16 '15 at 08:04
  • Look at http://www.npl.co.uk/reference/measurement-units/si-base-units/the-kelvin The national physical laboratory is an authoritative source for this question. – Anton Aug 14 '15 at 23:43

1 Answers1

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Official recommendation is to use space.

The value of a quantity is written as a number followed by a space (representing a multiplication sign) and a unit symbol; e.g., 2.21 kg, 7.3×10² m², 22 K. This rule explicitly includes the percent sign (%) and the symbol for degrees of temperature (°C). Exceptions are the symbols for plane angular degrees, minutes, and seconds (°, ′, and ″), which are placed immediately after the number with no intervening space.

https://en.wikipedia.org/wiki/International_System_of_Units#General_rules

Andrew Leach
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agni10
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  • You might like to improve your answer by citing your source with a link. The wording sounds like what I remember from the SI style guide, which for anyone working on these matters is worth reading and not (quite) as dull as it sounds. +1 from me though. – Chris H Aug 14 '15 at 19:10
  • To be more specific, this quote is from Wikipedia which refers to "the SI brochure" (from the International Bureau of Weights and Measures) and "the NIST brochure" (The National Institute of Standards and Technology), in the footnotes. – Henrik N Aug 14 '15 at 19:10
  • As it was my first answer, I was still trying figure out the formatting. Added the reference. – agni10 Aug 14 '15 at 19:18