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The Difference Between “Could Have” and “Might Have” in English

“Could” and “might” are modal verbs in English, meaning they are used together with main verbs to express different meanings such as possibility, ability, permission, request, offer, criticism, condition, and more.

For example: He could speak five languages (ability)

“Could” is the past tense of “can,” while “might” is the past tense of “may.” This means they are used to express what was possible or permitted in the past. For example:

He could go to the cinema yesterday (past possibility)

Using “could” in a sentence gives the event a greater likelihood than “might.” This means “could” shows that something was more possible or more probable in the past than “might.” For example:

She could have won the lottery. (It was quite possible but we don’t know if it happened.)
They could have seen a UFO. (It was reasonably possible but we don’t know if it happened.)

“Might” shows that something was less possible or less probable in the past, or we are not sure about it. For example:

She might have won the lottery. (It was also possible but very unlikely, or we don’t know for sure.)
They might have seen a UFO. (It was also possible but very unlikely, or we are not sure.)

In this article, let’s look at the usage of “could” vs “might” in more detail, including with “+have.”

The Difference Between “Could” and “Might”: Usage Rules

“Could” and “might” both belong to modal verbs in English, which are used to express different meanings such as possibility, ability, permission, request, offer, criticism, and condition. Here are some rules and examples of their usage:

Possibility: “Could” and “might” indicate that something is possible but not certain. They are almost identical in this meaning, but “might” is slightly more uncertain and less probable than “could“. For example:
- He could be at home. (It’s quite possible but we don’t know for sure.)
- He might be at home. (It’s also possible but less likely, or we are not sure about it.)
- It could rain later. (It’s possible since the weather is unstable.)
- It might rain later. (It’s also possible but less expected, or we have no control over it.)
Ability: “Could” is used to show the ability to do something in the past. “Might” is not used for this meaning. For example:
- She could speak five languages. (It was her ability in the past.)
- She might speak five languages. (It’s a present possibility.)
Permission: “Could” and “might” are used to request permission to do something. They are both more polite and formal than “can.” “Might” is the most polite and least direct. For example:
- Could I borrow your pen, please? (A polite request for permission.)
- Might I borrow your pen, please? (A very polite and indirect request for permission.)
- Could we come a bit later? (A polite request for permission.)
- Might we come a bit later? (A very polite and indirect request for permission.)
Note: When responding to such requests, we don’t use could or might, but use can or may instead:
- Could I borrow your pen, please? – Yes, you can./No, you can’t. (Or Yes, you may./No, you may not.)
- Might I borrow your pen, please? – Yes, you can./No, you can’t. (Or Yes, you may./No, you may not.)

Request: “Could” and “might” are used to make polite requests to do something. They are both more polite and formal than “can.” “Might” is the most polite and least direct. For example:
- Could you help me with this homework? (A polite request.)
- Might you help me with this homework? (A very polite and indirect request.)
- Could I ask you a personal question? (A polite request.)
- Might I ask you a personal question? (A very polite and indirect request.)
Offer: “Could” and “might” are used to make an offer of something. They are both more polite and less direct than “can.” “Might” is the most polite and least direct. For example:
- We could go to the cinema tonight. (An offer.)
- We might go to the cinema tonight. (A very polite and indirect offer.)
Criticism: “Could” and “might” express dissatisfaction or criticism. They are both used with have + past participle form of the verb. “Could” is stronger and more accusatory than “might.” For example:
- He could have been more careful. (Expresses criticism, accusation)
- He might have been more careful. (Expresses doubt, irony)
Condition: “Could” and “might” are used for conditional statements. They are both conditional forms of “can” and “may.” They are used with if + past simple in the main clause. For example:
- If I had more time, I could learn more languages. = If I had had more time, I would have been able to learn more languages. (Expresses past ability.)
- If I had more time, I might learn more languages. = If I had had more time, I may have learned more languages. (Expresses possibility but uncertainty in the past.)
- If she studied harder, she could pass the exam. (Expresses past ability.)
- If she studied harder, she might pass the exam. (Expresses past uncertainty.)

“Could Have” and “Might Have” – Formation and Differences

Both expressions are formed with a modal verb (‘could’ or ‘might’) plus ‘have’ plus the verb in past participle form.

Examples:

‘Could Have’: “I could have gone to the party, but I was too tired.”
‘Might Have’: “He might have left already because his shoes are not here.”

Grammar: ‘Could have’ and ‘might have’ are used to express an action that could have happened in the past but did not happen (in the case of ‘could have’) or an action whose occurrence we are unsure about (in the case of ‘might have’).