The context is that a group of us asked a friend to come and have a breakfast, instead of study for a test (bad influence, I know). Initially she said she wouldn't come, but after some badgering on our part she gave us some leeway.

Which of these responses is grammatically correct?

  1. If I change my mind, I let you know.
  2. If I change my mind, I'll let you know.
  • Given in writing, it will be the first. In speech, the consonants can merge so both the answers sound the same.
    – Kris
    Feb 22 '12 at 12:18

The second sentence is definitely the correct one:

If I change my mind, I'll let you know.

You or your friends are probably confused because when "I'll let" is spoken, all those "L"s blend together and sound like "I let". Don't be fooled by that.

Try the same tense with different words. Which sound correct to you?

Incorrect: If I change my mind, I buy the product.
Correct: If I change my mind, I'll buy the product.

Incorrect: If I win a lottery, I donate the money.
Correct: If I win a lottery, I'll donate the money.


The first one is a continuous tense, indicating that any time you change your mind, you already do - and will continue to - let them know. This is probably not what is intended.

The second and correct one means that in the case where you change your mind, you will at that point, let them know. In fact, the context is also important, because it means that if you change your mind about this particular issue, you will inform them. In the first case, because this is a continuous use, the context is not necessarily implied.

  • I don't think I can agree with this. What you say is true when the sentence starts with when, not if. Think about it and you'll agree with me.
    – Frantisek
    Feb 22 '12 at 9:41
  • Nope - I have thought about it and I still disagree. Feb 22 '12 at 10:37
  • 1
    @SchroedingersCat: The first sentence doesn't contain a continuous tense. I suppose you mean "a repeated action" as in "If he gets there before me, I always wait for him."
    – Irene
    Feb 22 '12 at 11:25
  • 1
    +1: @SchroedingersCat: I think the more typical grammatical term used here is "habitual" rather than "continuous". Feb 22 '12 at 12:30

For me, the first response was the correct one, because I used to hear and read that from locals when I was living in UK.

On the other hand, a friend of mine sent me this link about the conditional. The first two paragraphs (type 0 and type I) show why my friend thinks that the second response in future tense is the correct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.