When to use WILL
In other cases, where there is no implicit or explicit connection to the present, use WILL:
1. For things that we decide to do now. (Rapid Decisions)
This is when you make a decision at that moment, in a spontaneous way.
I'll buy one for you too.
I think I'll try one of those. (I just decided this right now)
2. When we think or believe something about the future. (Prediction)
My team will not win the league this season.
I think it will rain later so take an umbrella with you.
Note: You can use both Will and Going to for making future predictions.
3. To make an offer, a promise or a threat.
I'll give you a discount if you buy it right now.
I promise I will behave next time.
I'll take you to the movies if you'd like.
4. You use WON'T when someone refuses to do something.
I told him to take out the trash but he won't do it.
My kids won't listen to anything I say.
My car won't start.
