Use of CAN and COULD in English: can vs could differences

Many students get confused about what to use: can or could. Can and could are modal verbs (auxiliary) that support the main verb. Both can and could often confuse English learners as they are generally used interchangeably. In most cases, their meanings remain the same, but in some cases, they render completely different meanings.

In this article, we will master the use of can and could, and what the difference between can and could is.

Can and could are generally used to talk about the capabilities of a person or a thing. The core meaning of can or could is “to be able to do something.” But apart from this use, they can be and are used in different ways. Let’s get to know them.

Common use of can and could

Let’s look at all the situations where can and could are used.

1. To show general abilities/capabilities

Both can and could are used to talk about the general abilities and capabilities of a person. Use CAN to talk about the capabilities and abilities of a person or a thing in the present.

• I can beat you in a street fight.
  (I have the ability to beat you in a street fight.)

• He can speak many languages.
  (He has the capability of speaking many languages.)

• Can you understand what she says?
  (A question about your capability.)

• My father can’t take anything against his political party.
  (My father does not have the ability to take anything against his political party.)

• I could finish the bottle yesterday, but you did not let me.
  (I had the ability to finish the bottle yesterday.)

• Rohan could speak English when he was living with me.
  (Rohan was capable of speaking English in the past; he may or may not be able to do it now.)

• She could speak 5 languages fluently in her childhood.
  (She was able to speak 5 languages fluently in her childhood; she may or may not be capable of that now.)

• My brother could beat me in a race when I was in school.
  (He had the capability to beat me in a race in the past. He probably does not have it now.)

• I could not pick up your call. I was in a meeting.
  (I was not able to pick up your call.)

2. To make a request

To make a request, both can and could are used.

• Can you please teach me how to dance?
• Can I come with you?
• Can you please guide my son about career choices?

• Could you please teach me how to dance?
• Could I come with you?
• Can you please guide my son about career choices?

3. To give and take permissions

When you want to take permission from a person or people, you can either use can or could. Let me show you what the difference is.

Examples of can to take permissions:

• Can I use your laptop for a minute?
• Can we check out your house?
• Can I kiss you? 
• Can they call you in the evening?

Examples of could to take permission:

• Could you please teach me how to dance?
• Could I come with you?
• Can you please guide my son about career choices?

DIFFERENCE: could is considered more polite and formal when it comes to taking permissions. When taking permission from someone you don’t know well or want to be extremely polite and nice with, use could. Use can when the people you are talking with are already known to you and know you well. You don’t have to be very formal with them.

• You can kiss me.
• You can bring your friends. But tell them not to smoke and drink here.
• His friend can join the company on one condition: he must know how to dance.
• Max does not have to live in a PG. Tell him he can live in my house.

4. To talk about possibilities

Both modal verbs can and could are used to talk about possibilities of events, but in different situations. To talk about a general possibility, use can. And to talk about a specific possibility, use could.

General possibility: it refers to a possibility of an event which is not specific. The place, time, and people involved are not specific in a general possibility.

Examples of can in general possibility:-

• She can be very rude at times.
  (It is not specific when she gets rude, who she gets rude to. It is a general event.)

• Owning a pet can be pretty expensive.
  (The time, place, and the people involved are not specific. It is a general statement.)

• A fight can break out anytime.
  (We don’t know when it happens, who are involved in this, and what is the place.)

Specific possibility: It is more specific than a general possibility. The time, place and the people are generally specific here.

Examples of could in specific possibility:

• He could be on the train with Sam.
  (The situation is pretty specific: we are talking about the possibility of someone (known) being on a specific train with a specific person.)

• I could come to your place tomorrow.
  (The event is specific: specific place and specific time)

• Bangladesh could beat India in the next match.
  (We are talking about the possibility of an event that is specific.)

5. To give suggestions

Use could to give suggestions.

• We could wait here until he comes. (What to do now?)
• You could talk to the police about this. (Giving a suggestion)
• We could order some food and watch some movies together if you like. (Giving a suggestion)

Examples of COULD as the past form of CAN

• I could finish the bottle yesterday, but you did not let me. (capability)
• You could enter my house without my permission. Why didn’t you? (Possibility)
• He could kill you, but he didn’t because he knows you are my friend. (Possibility)
• We could not finish the task in time. (Inability) 
• She could not talk to her parents about me. (Inability)

COULD in conditional sentences

COULD is also used in conditional sentences to refer to the past, present, and future.

Examples of could in conditional sentences:

• I could have saved her if I had had enough money. (3rd conditional sentence)
• If I were a Muslim, she could marry me. (2nd conditional sentence)
• If the boys had been taught properly, they could have cleared the exams. (3rd conditional sentence)
• If you study hard, you could clear the exam. (conditional 1 sentence)

• If you work hard, you can/could clear the exam.
• If it does not rain, I can/could visit you tomorrow.

Difference between CAN and COULD

Numbers	CAN	COULD
1.	Used to indicate abilities/capabilities, orders, permissions, requests, and possibilities (general) in the present and the future.	Used to indicate abilities/capabilities requests, taking orders, and possibilities(specific) in the present, the past, and the future.
2.	It is considered a little informal.	It is considered very polite and formal.
3.	Can is used to refer to the present and the future.	Could can be used in all the tenses: present, past, and future
4.	CAN can’t be used in the past tense.	Could is the past form of ‘can’ and be used to refer to the past tense.
5.	Not used in the conditional sentences.  (2nd & 3rd)	Used in all the conditional sentences.  (1st, 2nd & 3rd)
6.	Used to give orders.	Not used to give orders.
7.	Not preferred to give suggestions.	Used to give suggestions.
8.	Used to talk about general possibility of events.	Used to talk about specific possibility of events.

Watch my Youtube video on can vs could:

Related YouTube lessons

• Conditional sentences Type 1, 2, 3: https://youtu.be/mDX66QhFZBU
• Mixed conditional sentences: https://youtu.be/pytgd6HEbBs