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Can vs. Could: Learn the Difference

Updated on March 23, 2023Grammar

People often use can and could interchangeably, even though the words have slightly different meanings. Luckily, the rules about when to use can vs. could are pretty straightforward.

Both are modal verbs used to express ability or possibility; they can also be used to ask for permission.

When you’re talking about the possibility of something happening in the future, use can if something is very likely to happen. Could, on the other hand, should be used for things that have an equal chance of not happening. When you’re referring to someone’s ability to do something, use can in present-tense scenarios and could in past-tense situations.

Avoid making a grammatical blunder by reading our piece on the differences between can vs. could.

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What’s the difference between can and could?

Unlike some other commonly confused words, such as to vs. for, can and could have only two main differences: tense and likelihood.

Can is the present tense modal verb used to express someone’s ability.

I can book that appointment for you right now if you’d like.

Could is the past tense modal verb used to express someone’s ability.

Harpreet could have pitched a perfect game if his manager had kept him in.

Both verbs can also be used to express the likelihood of something happening in the future tense, which is when most people often confuse the two. Can is used to describe scenarios that are more likely than not to happen, while could is used for scenarios that are less probable.

You can get an upset stomach from eating too many habaneros.

I really think Steve could win this season of the Great British Baking Show.

Read more: There are similar rules for was vs. were.

There is a third difference between the two when it comes to asking permission, though this is more of a colloquial difference than a grammatical one. Can is often seen as more casual, while could is read as more polite and formal.

Can we get ice cream after tacos?

Could you reach the box on the top shelf for me, please?

Using can in a sentence

There are three times you can use can in a sentence—and the first is this exact sentence. Can expresses someone’s ability to do something, so use it when you want to say that someone is able to do something right now.

When referring to the possibility of something happening, can should be used if there’s a good chance that it will happen.

You should also know that can is seen as an informal way of asking permission.

Using could in a sentence

Use could if you’re describing someone’s ability in the past tense.

Consider could a realist when it comes to possibilities—something might happen, but it also might not.

Could is seen as more formal when asking for permission.

Can vs. could examples

Examples of can:

  • I can open that door for you.
  • You can damage your car’s engine if you drive around with low motor oil.
  • Can we pick a new restaurant for date night?
  • You can pick whatever restaurant you like.

Examples of could:

  • Mario could have gone to any college he wanted, but he chose UConn because that’s where his dad went.
  • I could win the Chicago Marathon if I train hard enough.
  • Could you have someone carry my bag upstairs?
  • I think we could outrun those wolves.

Can vs. could FAQs

What’s the difference between can and could?

Can is used to refer to someone’s ability in the present tense, whereas could is used in the past tense. Can also implies that something is very likely to happen, while could means it could happen but also might not happen. Can is used when you want to ask permission in a casual setting, and could is seen as more formal.

How do you use can in a sentence?

Use can to indicate someone’s ability in the present tense or indicate that there is a good chance of something happening. Can is also used to ask for permission, but it’s seen as more casual and shouldn’t be used in formal settings.

How do you use could in a sentence?

Use could to refer to someone’s ability in the past tense or indicate that something might happen, but it also might not happen. Could is used to ask for permission in formal interactions.

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