Grammar > Verb tenses > Future: Will vs Going to

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Differences

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1.   "Will" = decision at time of speaking; "Going to" = after decision is made. 

 

However there are times when they are used interchangeably. 

 

• I'll have orange juice.

• I'm going to have orange juice.

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• I'll book my tickets this afternoon.

• I'm going to book my tickets this afternoon. 

 

The differences are pretty subtle in these examples. This is because the hearer cannot always tell exactly when the speaker made the decision.​

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Let's compare them in more specific situations.

 

Offer to do something:

• "I'll help you with that."

• "I'm going to help you with that."

 

Both are acceptable. However, "going to" sounds more determined here because it implies the speaker has planned to help you beforehand.

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Ask someone to do something:

• "Will you help me return these books?"

This sounds like a normal request.

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• "Are you going to help me return these books?"

This sounds like a demand in the form of a question.

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Agree to do something:

• "I'll walk you to the library."

• "I'm going to walk you to the library."

 

Again, "going to" sounds more determined.

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Promise to do something:

• "I'll buy you coffee afterwards."

• "I'm going to buy you coffee afterwards."

 

To me, both are acceptable. Although "going to" still sounds determined, in the case of making promises, sometimes it is a good thing for one to be determined to keep their promises.

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Refuse something:

• "I won't be able to have coffee afterwards."

• "I'm not going to be able to have coffee afterwards."

 

I think the difference here is quite subtle and both are acceptable. However, "won't" sounds more direct, and "not going to" sounds like they gave it more consideration.

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From all of these examples, "will" and "going to" can be used interchangeably but it can also affect how polite the speaker comes across. With the exception of negative sentences, "going to" can come across as determined and sometimes demanding as in the case of asking someone to do something. 

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2.   Predictions: "Will" = guess; "Going to" = based on evidence. 

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For everyday English however, these are often used interchangeably. 

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• "Do you think we'll be able to get tickets?"

• "Do you think we're going to get tickets?"

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There are situations when "going to" should be used instead of "will." These situations are related to the weather, the weather forecast, or medical if they're based on symptoms. 

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• "Look at those dark clouds, It's going to rain soon."

• "According to the weather forecast, it's going to rain this weekend."

• "I feel terrible, I think I'm going to be sick."

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However, it is also not so weird if I say:

• "Look at those dark clouds, it'll rain soon."

• "According to the weather forecast, it'll rain this weekend."

• "I feel terrible, I think I'll be sick."

 

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3.   "Will" = certainty in the future; "Going to" = accurate predictions.

 

Although there is a difference, they are used interchangeably in this way. Compare the following examples.

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• "The sun will rise at 7.14am."

• "The sun is going to rise at 7.14am."

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• "I'll turn 35 this month."

• "I'm going to turn 35 this month."

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• "The bomb will explode."

• "The bomb is going to explode."

 

Regarding bombs, "will" sounds like a fact because it is the nature of bombs to explode. "Going to" sounds like something that is about to happen - so this is a prediction based on current evidence. 

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4.   Conditional sentences about the future: "Will" = possible situations; "Going to" = definite/certain situations.

 

"Will" and "going to" are not interchangeable when talking about possible or hypothetical situations. However, for definite or certain situations, "will" and "going to" are interchangeable. 

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Possible situations:

• "If he gets promoted, he'll buy a new car." 

Not - "If he gets promoted, he's going to buy a new car." 

 

The second sentence is confusing. He is planning to buy a new car even though he does not know whether he will be promoted.

 

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Definite/certain situations:

• "When he gets home, he's going to call his mom."

• "When he gets home , he'll call his mom."

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See also:

• Future: Going to

• Future: Will

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