Simple Future Tense

Future
English is sometimes described as having a future tense, although since future time is not specifically expressed by verb inflection, some grammarians identify only two tenses (present or present-future, and past). The English "future" usually refers to a periphrastic form involving the auxiliary verb will (or sometimes shall when used with a first-person subject; see shall and will). There also exist other ways of referring to future circumstances, including the going to construction, and the use of present tense forms. For particular grammatical contexts where the present tense substitutes for the future,

No Plan

We use the future simple tense when there is no plan or decision to do something before we speak. We make the decision spontaneously at the time of speaking. Look at these examples:

Hold on. I'll get a pen.
We will see what we can do to help you.
Maybe we'll stay in and watch television tonight.
In these examples, we had no firm plan before speaking. The decision is made at the time of speaking.

We often use the future simple tense with the verb to think before it:

I think I'll go to the gym tomorrow.
I think I will have a holiday next year.
I don't think I'll buy that car.
Prediction

We often use the future simple tense to make a prediction about the future. Again, there is no firm plan. We are saying what we think will happen. Here are some examples:

It will rain tomorrow.
People won't go to Jupiter before the 22nd century.
Who do you think will get the job?
Be

When the main verb is be, we can use the future simple tense even if we have a firm plan or decision before speaking. Examples:

I'll be in London tomorrow.
I'm going shopping. I won't be very long.
Will you be at work tomorrow?