Future Simple With "Will": 

This future simple timeline shows a prediction for the future not based on evidence. The "will" future is based on spontaneous decisions or predictions, and can be shown on a timeline with a single X to mark the event.

Affirmative (Positive)

I will play football tonight.

Form: Subject + will + verb (infinitive)

Negative

I won’t play football tonight.

Form: Subject + will + not + verb (infinitive)

Question (Interrogative) 

Will you play football tonight?

Form: Will + subject + verb (infinitive)

Predictions

We use will to talk about something we think that will happen:

I think he’ll be there.

He will be a good teacher.

We use be going to to talk about something that is very near to happen or that we see is going to happen (there is present evidence)

Don’t speak so loud. You’re going to wake the baby!

The doctor said I’m going to be fine after the surgery.

Decisions

We use will for decisions that we take at the moment of speaking (instant decisions).

‘Oh, we don’t have any coffee left.’ ‘Don’t worry, I’ll buy some.’

We use be going to for decisions that we have already taken at the moment of speaking (intentions or plans).

‘Why are you taking that book?’ ‘Because I’m going to read it while we stay at the beach.’

Arrangements

We often use the present continuous to talk about future events that have already been planned or decided. When we use the present continuous for arrangements, we must always include when (at 7, this evening, next month, etc.) in the sentence.

I’m seeing my mom at 9 a.m.

We are buying a new apartment next month.

I’m flying to Rome in December, I hope you will be there.

We can also use be going to for future arrangements.

I’m going to have lunch with David today. 

Future time clauses (when, as soon as, until, before, after)

Use the present simple to talk about the future in sentences with when, as soon as, until, before and after.

I’ll retire when I‘ll be 70. 

I’ll retire when I‘m 70. 

I won’t call you until I will arrive. 

I won’t call you until I arrive. 

Other uses of will

Promises and refusals

I will help you whenever you need me.   

I won’t lend him my car. 

Future facts

The president will visit the Vatican next November.

Offers

We use I will in statements or shall I in questions.

I’ll carry that bag for you.

Shall I organise the meeting?

Suggestions

We use shall we…?

Shall we eat out today?

Requests

When we ask someone to do something for us.

Will you open the door, please?

May or might as a future form

We use may or might for possible actions in the future (when ‘we are not sure’). Compare:

I’ll be late for dinner today. (=I am sure.)

I might be late for dinner today. (=It’s possible, but I am not sure.)

I’m going to Denmark next September. (=Sure.)

I might go to Denmark next September. (=Not sure.)

We use may or might for things that will possibly happen in the future, but we are not too sure. It’s like a prediction about something that we think perhaps will happen.

The economy might suffer a global recession next year.

Temperatures may go up next week.

We use may or might not for actions or things that will possibly not happen.

She looks very tired. She might not come with us.

We may not have enough time to finish the report for tomorrow.