britannica.com says "weight" is uncountable here:
(1) My weight is 150 pounds.

But a user on ell.stackexchange.com says "speed" is countable here:
(2) The runner's speed was 6 kilometers per hour.

To me, the structure of sentences (1) and (2) is the same.
Then why is "weight" uncountable whereas "speed" is countable?


3 Answers 3


It is impossible to determine from the example if the words are countable or uncountable. There is no grammatical clue or difference in meaning.

Would it be possible to use a plural in these sentences? Yes (but perhaps odd) Imagine a person whose weight went up and down:

My weights are 150lb in the morning and 155lb in the evening.

Or a runner with different speeds:

The runner's speeds are 6km/hr at a jog but 12km/hr when sprinting.

So in principle, both these could be countable. But these are very odd, artificial constructions.

You can't tell just from the structure if a word is countable or not. Consider:

My cat is white.

My rice is white.

But rice, you know, is uncountable, whereas cat is countable.

But "coffee" you know can be both countable "a coffee" and non-count. So tell me, which one is it:

My coffee is white.

I say you can't tell, and it doesn't matter.

  • If a person's weight goes up and down from the am to the pm, it is still only weight. My weight is x in the am and y in the pm.
    – Lambie
    Dec 4, 2023 at 23:30
  • Yes, weight can mean the amount of mass, or the number that represents it, There are two numbers, but the weight is still just weight. So it would normally be uncountable, if you were talking about the numbers, there are two, so plural. But in the singular, there is not way of determining nor is there any different understanding of what is being communicated.
    – James K
    Dec 4, 2023 at 23:34
  • My weights are 150lb in the morning and 155lb in the evening. That is just nuts, sorry. My weight is x in the morning and y in the evening. Very obvious. Now, you might say: Those weights are odd since they differ by a full five pounds.
    – Lambie
    Dec 4, 2023 at 23:38
  • 1
    Did I understand you correctly?: "Weight" in (1) can be UNCOUNTABLE because we can say: "My weight is different: 150lb in the morning and 155lb in the evening." "Weight" in (1) can be COUNTABLE because we can say: "My weights are different: 150lb in the morning and 155lb in the evening." "Speed" in (2) can be UNCOUNTABLE because we can say: "The runner's speed is different: 10km/hr at a jog and 30km/hr when sprinting." "Speed" in (2) can be COUNTABLE because we can say: "The runner's speeds are different: 10km/hr at a jog and 30km/hr when sprinting."
    – Loviii
    Dec 5, 2023 at 15:54
  • @Loviii The plural one with weights in the am and pm is simply inaccurate. The same goes for speed. Both, in these contexts.
    – Lambie
    Dec 5, 2023 at 20:42

A non-countable noun is one that you don't normally pluralise. There are exceptions to most common non-countable nouns. The frequently-cited example is water. Typically, all liquids are mass nouns, but if you break them down into quantities - eg bottles or glasses - then you can count them. It's normal to order "three beers" or even "three waters" proving that liquids can be pluralised, but what you're really counting is the glasses and bottles the liquid comes in - the individual quantities.

Weight, in the context of your example, is an abstract noun - an intangible, non-physical thing - and these are typically non-countable. "My weight" refers to the concept of weight as a quality a person has, in the same way that 'colour' is abstract in a statement like "my hair colour is brown". But, as with my example of liquids, when you can assign a measurement of weight to multiple things then you can pluralise it. For example you could use the singular noun in a phrase like "I recorded the weight of each family member", but use the plural in a phrase like "then I added all their weights together". Again, although we are pluralising 'weights' what we are really counting is the individual measurements of weight taken for each person. Don't be confused by the noun 'weight' to mean the pieces of metal used on scales and in gymnasiums. Those are a tangible thing, which is why you can count them and it is common to say "I'm lifting weights".

Speed is no different. It is an abstract noun. It is a concept, not a tangible thing. We use it singularly to refer to the concept of speed, but it can be pluralised when referring to individual measurements of speed.

  • You wrote: "Weight, in the context of your example, is an abstract noun - an intangible, non-physical thing - and these are typically non-countable." But we could also say the same words about "speed" from (2). That is, you consider "speed" uncountable too, right?
    – Loviii
    Dec 4, 2023 at 23:29
  • weight is a non-physical thing? It is a mass noun, but not abstract or non-physical...
    – Lambie
    Dec 4, 2023 at 23:31
  • 1
    @Loviii yes, exactly. Both weight and speed are abstract and they should be treated the same. They can both be uncountable when referring to the measurement in general, but as soon as you start recording measurements and referring to those individual measurements of speed or weight it is possible to count them.
    – Astralbee
    Dec 5, 2023 at 8:53
  • 1
    @Lambie Of course it is abstract, it is a quality. Here is a guide for English students you might find helpful: english-for-students.com/abstract-noun.html
    – Astralbee
    Dec 5, 2023 at 8:57
  • We don't measure "peace" (Uncountable), "compassion” (U), "friendship" (Countable), or an "idea" (C) because they are concepts; intangible and non-physical. The word "air" is also non-tangible. We can't see or touch it as if it were a solid but it's classed as a concrete noun because it “exists“. The nouns "weight" and "speed" are both perceivable, and in the case of "weight", it is physical as we know when something is light or heavy. Additionally, we are able to assess speed and weight accurately, so if these qualities are measurable, why are they classified as abstract?
    – Mari-Lou A
    Dec 5, 2023 at 10:27

The simplest answer to this, that will involve the least "hair-splitting," is "because they are." They're different words. Although it would seem intuitive that they ought to behave the same way, they're not compelled to.

First of all, even "speed" is used much more often in a non-count way than in a count way. We usually talk about "speeds" only when comparing statistics, like "here are the speeds of the top five horses in the race." Now... if I had to talk about the horses' weight... I could maybe imagine saying "Here are the weights of the top five horses." But it would be a little odd. But so would "Here is the weight of the top five horses"; that would make sense only if I'd added the weights together. I would be more inclined to recast the sentence, "Here is the weight of each of the top five horses." And there's no explanation for why other than... words behave differently sometimes.

  • Astralbee said "weight" in (1) and "speed" in (2) are both uncountable. James K said "weight" in (1) and "speed" in (2) can be both uncountable and countable. You wrote "because they are". That is, you consider "weight" in (1) uncountable and "speed" in (2) countable. Could you explain to me please why you think "speed" in (2) is countable?
    – Loviii
    Dec 6, 2023 at 0:46
  • @Loviii I think you've mistaken Astralbee's overall position; they said "it can be pluralised when referring to individual measurements of speed." Dec 6, 2023 at 17:35
  • @Loviii Be warned: discussion of "count" and "noncount" nouns is tricky. It only describes what usually happens, and it's often possible to find exceptions. You can also find intentional "misuses," or extended uses. Musicologists have been using the term "musics" intentionally for decades to indicate just how encapsulated a music-culture can be or to communicate a pluralistic rather than universalist approach to the topic. Dec 6, 2023 at 17:43

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