I know that the first is correct. Is the second correct too? Why?

And two more examples to make it clearer:

I know the tower height


I know the tower's height


I know height of the tower

  • Do you know Big Ben height?
    – TimR
    Commented Jun 22, 2015 at 20:39
  • 1
    The possessive ('s or of the) seems mandatory to me.
    – Archa
    Commented Jun 22, 2015 at 21:08
  • @Archa in both (Bryan and tower) cases? Commented Jun 22, 2015 at 21:10
  • 1
    An apostrophe is definitely required. Otherwise, an alternative is "I know the height of the tower".
    – JMB
    Commented Jun 22, 2015 at 21:24
  • 1
    In spoken discussion of science/engineering, the article could be omitted: "To calculate the wind load, I need to know Tower Height, Tower Width and Wind Speed. I can get Tower Height by multiplying ....." This works if we think of "Tower Height" not as an attribute of the tower, but instead as the name of a variable in an equation. This is very common in the U.S.
    – Adam
    Commented Jun 22, 2015 at 21:35

2 Answers 2


English is flexble and allows many nouns to function as modifiers, but it has a subtle effect on meaning.

I know the tower height.

Here, I understand that height is a noun, and tower is an adjective answering the question height of what? or what kind of height?.

But this makes it seem like tower height as in "the height of a tower" is an important idea or concept on its own and that the listener/reader ought to be familiar with that or the reason for that - e.g. in this case, heights of towers seem to be something that you work with so much that you are shortening the words used to express it.

Usually you want to avoid this unless you are getting into the technical jargon of a profession or "shop talk".

Now, given the above, if you were to do this with a proper noun, you would be de-personalizing, as though the proper noun is just a thing, or a non-human object. And of course, since it's a modifier, you still need your article in front of it.

I know the Bryan height.

Here, it seems you are saying that Bryan is not a real person - I would guess it's some technical jargon, some aspect of a craft or profession - like "Pythagorean theorem" or similar.


I know the tower's height

I know the height of the tower

mean the same. X's Y can mean "Y physically belongs to X" or "Y that which is an attribute/quality belonging to X".


All three are correct. In all three cases, "height" is modifying tower.

In "the tower height", "tower" is modifying "height". When a noun acts like an adjective, it is called a noun adjunct or attributive noun.

In "the tower's height", "height" is an attribute that the tower possesses. The possessive can be used with abstract ownership as well as literal ownership, and so using the possessive makes sense, in the same way you could say "Her intelligence" or "John's weight".

As a native AmE speaker, with the tower examples, my frequency of using them would be in reverse order; some of it is convention, but "the height of the tower" is also less confusing. However, I think that's just because tower heights are not something one discusses all that often. With people, "I know the height of Bryan" sounds wrong and "I know Bryan height" sounds very wrong (you can't use people as an attributive noun); "I know Bryan's height" is pretty much the only option.

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