I encountered a question that went like this:

_______ fun it is to watch a 4D movie! A. What B. What a C. How D. How a

The key to this question is A.

I've read an explanation which says " ‘How’ can only precede an adjective in this kind of sentence, e.g. “How happy I am,” or an adverb in a similar kind of sentence, e.g. “How well you dance.” Since ‘fun’ is a noun, only “What fun it is” is correct. It’s the same construction as “What nonsense you speak” and “What an awful road this is.” However, “How much fun it is” would be correct.

Of course, some people might say “How fun it is,” but it’s still grammatically incorrect."

I was confused, because "fun" is also an adjective word. Then why is "how fun" grammatically incorrect?

  • @Jianbin Yin - The answer is not simple because of the history of the word "fun". It's late here so I can't answer now. I'll try to answer tomorrow. Nov 21, 2020 at 1:01
  • "What fun" is a standard phrase in English. "Oh! what fun it is to ride in a one-horse open sleigh!" The alternative "How fun" probably comes from a child, or some other person inexperienced in English.
    – GEdgar
    Nov 21, 2020 at 1:05
  • 1
    @chasly-supportsMonica In AmE "how fun" has come to be used more often than "what fun". It's even used ironically as in "Oh, how fun!"
    – Centaurus
    Nov 21, 2020 at 1:18
  • This is opinion-based. While A is definitely more common, C might be used in some contexts or "voices". Note that "what" has a sort of yes/no binary implication, while "how" suggests a sliding scale.
    – Hot Licks
    Nov 21, 2020 at 1:43
  • 2
    I expect most people would agree A is correct, while B and D are wrong. In my lifetime C has gone from being never heard and regarded as a mistake to being an accepted alternative in some variations of English. My opinion of this change is not relevant.
    – Peter
    Nov 21, 2020 at 3:35

2 Answers 2


It used to be that fun was a noun but not an adjective. See Ngram.

If fun were just a noun, you could not say

How fun it is to ...

Let's replace fun with the noun joy to see what happens:

What joy it is to ...
*How joy it is to ...

The second sentence sounds completely wrong (and doesn't even appear in Ngrams).

Unfortunately, the makers of the test are around fifty years out of date; fun is now well-established as an adjective in English. And for adjectives, you can use them with how

how easy it is to ...
how strange it is to ...
how pleasant it is to ...
how simple it is to ...

See Ngrams.

Lexico dictionary still classifies the adjective fun as informal, and it appears that usage of how fun it is to is still lagging what fun it is to (See Ngrams), but I expect it will catch up in a few more decades.


"How" is probably wrong as I imagine they were testing how to preface question vs statements.

In this vein, "How fun is it to watch a movie?" would possibly be what they were going for if (C) was correct.

"What fun is it to watch a movie!" is more of a declarative statement.

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