Are the following expressions both correct?

  1. I realized I had forgotten something.
  2. I realized having forgotten something.

What is the difference in the meaning (if any)?

  • 3
    The second expression doesn't seem grammatically correct.
    – Ébe Isaac
    Sep 14, 2016 at 8:28

3 Answers 3

  1. I realized [that] I had forgotten something.

This is grammatically correct, and probably what you wanted to say. realized is in simple past, so you are talking about something that happened in the past. had forgotten is past perfect, which places it before the realizing.

Note that realize is usually followed by a that-clause, although the that is often omitted.

  1. I realized having forgotten something.

On its own, this sentence is incomplete. having is a participle, and Having forgotten something is a participial phrase. Remember that realize requires a that-clause, and a phrase won't do. (A clause contains a verb, a phrase does not).

You might use it in a sentence like this, where there is an additional that-clause:

Having forgotten something, I realized that I would have to go back and get it.

  • The verb Realize is usually followed by a that-clause, that is the point. Thx :) Sep 14, 2016 at 8:50
  • 1
    The point, @Taiki is that your second sentence is ungrammatical. Sep 16, 2016 at 11:17

To realize is a reporting verb that can be followed either by "that- clause" or a clause starting with a question word (what, how, etc.). In "that-clause", that is often omitted, like it was in your first sentence.


Only then did I realize that he was telling the truth.

Looking in his eyes, I realized how serious he was.

Having read the letter, I realized what she really meant by saying that.

As for your second sentence, I can't but absolutely agree with JavaLatte.

P.S. The provided links will lead you to the lists of numerous reporting verbs and their usage to help you further your English.


In the first sentence at the moment you realized what you forgot, it was too late.

the door was already slammed when I realized I had forgotten my keys.

In the second one, having is the progressive form: at the moment you realized it, you could still correct the problem:

before I slammed the door I realized having forgotten my keys.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .