Learn English – ” will + verb ” against ” verb + ing ” in terms of future time

future-tense

Would you clarify which kind of given forms and when native speakers choose in order to speak about future. For example :
1) I'm doing it (I'm fixing the car tomorrow)
2) I'll do it (I'll fix the car tomorrow)
Are there any differences in meaning or grammar usage?
Are they exactly the same and interchangeable?

Best Answer

For future tense, "I'll do it" or "I will do it" is the one you need.

"I'm doing it" is an example of the present progressive (or present continuous), which means that it is happening in the present. So "I'm fixing the car" means that you're doing it right now.

However, when you use the present continuous with an expression of time, e.g. tomorrow, next week, over Christmas; then it can be used to express the future. So if you include the "tomorrow" then "I'll fix the car tomorrow" and "I'm fixing the car tomorrow" are pretty much equivalent.

More info here: http://www.bbc.co.uk/worldservice/learningenglish/flatmates/episode73/languagepoint.shtml