Present Simple and Continuous as Future

Present Continuous Tense

We can use the Present Continuous for future arrangements.

- I'm playing tennis with John tomorrow.
- I'm going to see my friends this evening.
- He's going to write a book.
- What are you going to do?

The use of the Present Continuous often stresses the involvement of other people in these arrangements.

Compare the future with going to, the Present Continuous and will:

- I'm going to visit my family this summer. - A future plan
- I'm meeting my family at 6.00. - A fixed arrangement involving other people.

Fixed arrangements can also use going to, but the Present Continuous is more common.

- I'll meet my family tomorrow. - Will is usually not used with arrangements and this sounds unusual.

Present Simple

We can also use the Present Simple for events that are part of a timetable or schedule. While the events are in the future, their existence is already established in the present so we use the Present Simple. 

- The train arrives at 8.00 this evening.
- There's a good concert on next week. 

- He has a doctor's appointment tomorrow. (It's part of his schedule)

Compare the difference between the factual Present Simple, and the more personal Present Continuous:

- We're having a party this weekend.
- The party starts at 6.00.