How do we pronounce the plural form of “kg” in a sentence?

Question

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?

Answer 1

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.

Answer 2

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.

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Note that

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

of course do exactly as Aishwarya A R explains.

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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.