Many grammar books debate the term 'future tense' in English. I hold the position that different ways can be used to express future time, depending on what exactly we want to indicate. I'm starting with two of the most vivid ways—using the present simple and present continuous tenses.
Present continuous (I am doing) with a future meaning
1)
I'm doing something (tomorrow) = I have already decided and arranged to do it.
For example:
A: What are you doing on Saturday evening? (not What do you do)
B: I'm going to the theatre. (not I go)
For example:
I'm not working tomorrow, so we can go out somewhere.
Ian isn't playing football next Saturday. He's hurt his leg.
2)
'I'm going to (do)' is also possible in these sentences:
For example:
'What are you going to do on Saturday evening?'
But the present continuous is more natural for arrangements.
3)
Do not use will to talk about what you have arranged to do:
For example:
What are you doing this evening? (not What will you do?)
Alex is getting married next month. (not will get)
4)
You can also use the present continuous for an action just before you begin to do it. This happens especially with verbs of movement (go, come, leave etc.)
For example:
I'm tired. I'm going to bed now. Good night. (not I go to bed now)
'Tina, are you ready yet?' Yes, I'm coming.' (not I come)
To be continued….