The concepts of will and going to future can be very confusing.
They both refer to events in the future and are often interchangable with no difference in meaning.
There are some rules as to when use which form.
Let's first look at how both tenses are created:
Formation
will future: will/will not (won't) + verb
Example: He will swim. He will not/won't swim
going to future: be (am/is/are) + (not) going to + verb
Example: He is going to swim. He is not/isn't going to swim.
Now, let's see when to use will and when to use going to future:
Usage
WILL |
|---|
Rapid Decision: I'm hungry. I will buy a sandwhich. |
Offer: That looks difficult. I will help you. |
Promise: Don't worry, I won't tell anyone your secret. |
Threat: I will tell mom if you don't stop! |
Refusal: They will not listen to anything I say. My car won't start. |
GOING TO |
|---|
Prior Plan - The decision was made before: I'm going to the lake next week. |
Evidence/Signs - It's very likely to happen: My stomach hurts, I am going to throw up. It's 7:1. They are going to win. |
Very near future - Something is about to happen: The bomb is going to explode! |
WILL or GOING TO |
|---|
Predictions: I think it will rain tomorrow. = I think it is going to rain tomorrow. |
