I look forward to hear/hearing from you

Tip: See my list of the

The word “to” in this phrase is slightly confusing because it is usually used to introduce a verb, as in “want to” or “have to”. However, “look forward to” follows a different pattern:

I look forward to [a thing you would like to happen; a noun]

Obviously, “hear” is not a thing, so it wouldn’t make much sense to “look forward to hear from you”. The thing you are looking forward to is “hearing from you”:

correct I look forward to hearing from you.

wrong I look forward to hear from you.

correct I am looking forward to hearing from you.

wrong I am looking forward to hear from you.

The reason is that “to” is just a preposition here and has nothing to do with the infinitive, just like in “listen to”—you would say “I listen to singing” rather than “I listen to sing”, wouldn’t you?

As for the question whether to use “I look forward to” or “I am looking forward to”, some people consider the two completely interchangeable, but most find the phrase with “look forward to” somewhat formal and best suited for formal correspondence, whereas “to be looking forward to” is more informal and friendly:

correct I look forward to hearing from you. (more formal)

correct I am looking forward to hearing from you. (more informal)