Could you tell me whether we need to say the first or the second of these?

  1. I want three kg of carrots.
  2. I want three kgs of carrots.

Is the first of those two choices the correct way of writing it?

  • 4
    Kilo and kilos. I'm afraid this is a very basic question. Users are always advised to do a little research before asking their questions. It took me longer to type this comment then to look up kilo in a dictionary.
    – Mari-Lou A
    Jun 14, 2015 at 5:19
  • Hi ML. "Kay gees" is completely commonplace in speech. you can trivially find even casual written examples duderocket.com/forums/topic/243 since that is how it is universally pronounced, in many areas and contexts. indeed, there are any number of similar usages - such "gees" (those acceleration thingies of which pilots speaketh of pulling).
    – Fattie
    Jun 14, 2015 at 9:16
  • come to think of it, the"written?" aspect is a great question. I'd love to know the best way to spell that in print, when, a character says it in quoted speech. (as I allude to below)
    – Fattie
    Jun 14, 2015 at 9:16
  • @JoeBlow - You're right about one thing – this would make a great question. :^)
    – J.R.
    Jun 14, 2015 at 11:16
  • Are you asking about pronunciation or orthography? Jun 20, 2015 at 10:36

2 Answers 2


I want three kg of carrot or I want three kilograms of carrot is correct.

'kg' is the S.I unit of mass and just like any other unit, it deserves to be treated the way it is. I've seen many internet articles that mention 'kgs' as the plural of kg, but it's wrong according to the rules of physics. Let me explain this to you:

3 kg = 3 x 1 kg

0.5 kg = 0.5 x 1 kg

Every quantity is best understood as a multiple of 1 unit (1 kg in this case). In this case, there is no question of adding an 's' to 'kg' to make it plural.

None of the other physical units are written in their plural form. When you abbreviate a unit to a symbol (newton==>N, metre/second==> m/s), you never add an 's' to make it plural. N (newton) is never converted in Ns to make it plural. In fact, it would be an anomaly to do so because it would mean newton-second(N s or N.s) which is not the unit of force, but of a whole new quantity called momentum.

When you expand the symbol out to its original name (kg==>kilogram, N==>newton), you have every right to use the rules of English grammar to convert it into its plural form.

For example: kilogram when converted to its plural form would become kilograms, and newton when converted to its plural form would become newtons.

Hope my explanation helped! If you have further queries regarding this topic, please let me know.

  • Hmm, this ia a perfect, flawless explanation of SI units (S.I. ? I don't know!) but the letters "kg" in the written example (even more so if it's a quote) are not SI units, right?
    – Fattie
    Jun 14, 2015 at 2:45
  • I didn't quite understand your question. Do you mean that 'kg' in the sentence provided by Anupama is not an SI unit? Jun 14, 2015 at 3:05
  • Hi Aish. Indeed, exactly correct. Note for example the OP may have used as an example "give me 500 gs" (grams - grams are not an SI unit) or "I think the car weighs about 2t" (nor are tons).
    – Fattie
    Jun 14, 2015 at 3:29
  • Oh...okay! I got it. My point was applicable to all physical units(though I mentioned that the SI unit of mass is kg). As you said, it's okay to use 'kgs' or 'gs' in speech but not in writing because it conveys a wrong meaning(gram-second, which, as far as I know, is a non-existent unit). Makes sense? Jun 14, 2015 at 3:51
  • 1
    @Aishwarya A H: on the contrary, kgs or gs (gms) is OK in writing, but weird/rare in speech. As others noted, it's said "kilo/kilos" (KEE-low) or "gram/grams". (....Oh, and I meant AmE only, not other flavors.) Jun 14, 2015 at 8:37

3 (hah hah) points to consider.

1) In speech it's commonplace to say "kay gees"; that is to say it's commonplace to pronounce the "s". You can and should so this. I believe it's especially common in Australia, say.

Exactly the same situation with, say, "kay-ems" ... "Are we there yet Dad?!" "Fifty kay-ems to go kids, shut the hell up and put another video on!"

2) Note that interestingly kilogram and kilograms are completely exchangeable. You can use either at any time. (Generally, you do not say the "s" if it is "exactly one" - but see footnote.)

This applies equally if you happen to abbreviate it, 50 km, 60 kms, 5 kg, 5 kgs. You can use either as you choose. (BTW, in the name of God, do ont use an apostrophe for plurals.)

3) If you are writing dialogue. In my opinion, dialogue should never include abbreviations or indeed numerals, as it is sort of .. well crazy.

As the monsoon swept the cracked windshield, he gently yet accidentally brushed her arm with his, but only the upper part, and whispered, "I wish I could lose two kilos, to be more sexy for you dear. But spot loss is just not scientific." Her sigh and the windshield wiper's sigh were coincident, yet beautiful, and her only reply was "Pass me another two thousand calorie pepsi, ma puce."

For me, in that dialog or any dialog using the symbols "2" or "kgs" or "kg" would really suck. You can't speak those symbols.

Or indeed

"Which biotoxin boss?" "Gimme two kaygees of yellow one, stat!"

Same again.

Dialogue on the page as "Pass me 5 nails" or "I'll buy 4 kg of carrots" for me is really bizarre. For me it's like -- if anything -- you're inserting a stage direction. Rather as if you saw in a novel:

"Pass me" - he uttered many complex scientific numbering terms in his throbbing Glaswegian accent - "of the yellow stuff, Jason! This world and others may depend on it!"

An interesting way to look at it: you would never in a fit use symbols like "5" or "kg" in poetry. Am I right?

There are 5 ways I love you
But only 4 ways I know you
They say love has no measure, aye,
but I can measure it, show me
one of these fools and I will show him
a kg of love and a ft.lb of passion.

of course it's silly, you'd want

There are five ways I love you
But only four ways I know you
They say love has no measure, aye,
but I can measure it, show me
one of these fools and I will show him
a kilogram of love and a foot-pound of passion.

So, for me a poetry example makes it clearer that in prose too, in dialog, you can't really use numerals and abbreviations.

Note that

if you are using SI Units, perhaps in a scientific context,

of course do exactly as Aishwarya A R explains.

Footnote 1. It's often said that in English you "don't say the s if it is exactly 1". This is naive. For example, if reading through a list like this: "Four kilograms, three kilograms, two kilograms, one kilograms, zero kilograms" - you would hit the "s" on the "one" as well. Secondly note that "exactly!" one is all-but meaningless. For example, in a more scientific setting if some physicists were saying "one point three zero eight kilograms", what they would mean is 1.308 plus or minus some error concept, with considerations of standard deviation shapes, blah blah; so - you could say - a thinking lab physicist (you know - as opposed to the dumbass ones) in stating the words "one" and "kilogram" would, in fact, not mean 1.0000 kg (which is meaningless anyway), because the "actual" weight might be 0.99767362 kilograms, so they would more likely say "one kilograms". So in this thrilling overheard sentence fragment from a lab .. "one point oh three kilograms .. one point oh kilograms ... nine point niner seven kilgrams .. we're there!" it would be completely normal (and if you will "scientific") to hit the "s" on the "one point oh" one.

  • 2
    For such an easy question, you sure go the long way round to answering it.
    – Mari-Lou A
    Jun 14, 2015 at 5:17
  • I didn't have any more time! I'm tortured by how to spell-out (or not) things like acronyms in speech. :O
    – Fattie
    Jun 14, 2015 at 6:59
  • 4
    Your claim that "one kilograms" is correct is patent nonsense. "One kilograms" is just as incorrect as "one apples" and the only time you'll ever see it is in the output of a computer program that didn't check for the singular. The argument that 1kg means 1.000 +/- tiny kilograms so you'd say "1 kilograms" is about as specious as saying that there might be a smaller apple hiding behind the one you can see, so you'd say "one apples" to cover the uncertainty. Also, I've never heard "niner" used outside the context of air traffic control. Jun 14, 2015 at 8:04
  • 2
    And in a scientific context, "kgs" is absolutely wrong: it means "kilograms times seconds". I think it's poor advice to suggest pluralizing SI unit abbreviations in any context: it seems on a par with any other advice that it's OK for people to make up their own spellings of words that have an established spelling. Jun 14, 2015 at 8:10
  • "I'm tortured by how to spell-out (or not) things like acronyms in speech." An acronym is, by definition, pronounceable without being spelled out. Jun 14, 2015 at 8:12

Not the answer you're looking for? Browse other questions tagged or ask your own question.