When to use Can vs Could in English

by Laura Jones
March 09, 2021
woman leanring english online and the difference between can and could

Can you use can and could correctly? It can be difficult to know which one to use sometimes. But we’re here to help! 

First, here is the basic difference: can is the present tense and could is the past. But, this difference has more consequences than just whether we are talking about the present or the past. So read this post to learn how to use can and could properly. 

Can and could for ability

  • We use can to talk about someone’s abilities or skills in the present, or generally. 

I can speak German. 

I can drive. 

I can’t speak French. 

I can’t drive but I’m going to learn. 

  • We use could to talk about someone’s ability in the past. 

I could speak German when I was at school. 

I could drive when I was 17. 

I couldn’t eat spicy food when I was younger, but I like it now. 

  • We also use can and could to talk about something we are able to do at a certain moment. 

I can see him – he’s over there. 

I couldn’t see him, there were too many people. 

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Can and could for permission

We use the verbs can and could to ask for permission to do something. Could is more formal and more polite than can. Think about the different situations when you might use can or could. We use can to give someone permission, and can’t to refuse permission. 

CanCould(Answer)
Can I go to the bathroom?Could I go to the bathroom?Yes, you can. 
Can I have a look?Could I have a look?No, you can’t look yet! 

Can and can’t are also used to talk about permission in general. 

We can cross the road at a level crossing. 

We can’t smoke indoors. 

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Can and could for possibility

Can is used to talk about general ideas of what is possible. 

It can get very hot in Sweden in the summer. (It doesn’t always get hot, but sometimes it does.)

People can learn basic English quite quickly. (This is generally possible – English starts simple and gets harder!)

Could is used to talk about things which might happen but we are not sure. 

It could rain tomorrow. (No one can know this for sure, but it’s always possible in the UK.)

They could be coming later. (Maybe they’re coming later, I’m not sure.)

Could have is used to talk about something that was possible in the past but didn’t end up happening. 

You could have called me! I would have made dinner for you too. 

Bob could have passed the exam if he’d tried harder. 

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Be careful! 

It’s easy to get confused when using can and could for possibilities. See these examples below to help you avoid some common mistakes. 

That girl can be mean. (Sometimes she is mean, I know this.)

That girl could be mean. (It’s possible, but I don’t know.)

Can’t is used to talk about things which are impossible. 

That can’t be Jenny, she always hated dogs. 

I can’t believe it! 

Offers

When we want to make an offer, we use can. This is most often seen in a question. 

How can I help?

Can I carry those bags for you?

Requests

We use both can and could to make requests. Could is more polite and more formal than can

Can you tell Mr Peters I’m here?

Could I have a cup of tea, please? 

Suggestions

When making suggestions, could is useful. 

We could go to the cinema

We could have a takeaway or I’m happy to cook. 

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Can and could in conditional sentences

As we said earlier, could is the past tense of can. Because could is seen as a past tense, it has functions like making things more polite. In conditional sentences, using a past tense makes something more imaginary or even lets us talk about things that are impossible. Compare these conditional sentences: 

0 – When it rains, we can splash in the puddles.

1 – If it doesn’t rain, we can go to the park. 

2 – If it wasn’t so cold, we could go to the park.

3 – If it hadn’t been so cold, we could have gone to the park.  

In the first sentence, we are talking about a general truth. This is the zero conditional, and we use can. We also use can in the first conditional to talk about the future. We use could in the second and third conditionals. In the second, we are imagining a situation; in the third, we are talking about changing the past – which is impossible! 

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