When it comes to English grammar, many ESL learners are confused about the difference between can and may. These two modal verbs are often used to express ability, permission, and possibility, but they are not always interchangeable. In this lesson, you’ll learn the core difference between can and may with clear rules and simple examples.
Can vs. May
- Can is mainly used for ability and informal permission.
- May is mainly used for formal permission and possibility.
Using Can
Can for Ability
We use can to talk about someone’s ability or capability.
- I can speak Spanish.
- She can swim very well.
- We can finish the project by Friday.
Can for Informal Permission
In everyday conversation, can is commonly used to ask for or give permission.
- Can I borrow your pen?
- You can leave early today.
Using May
May for Permission (Formal)
May is more polite and formal than can. It is often used in classrooms, exams, or formal situations.
- May I go to the bathroom?
- You may begin the test now.
May for Possibility
We also use may to express possibility (something is possible but not certain).
- It may rain later.
- She may arrive late.
- She may not be able to attend the meeting.
Note: In the last example, may expresses possibility, and be able to refers to ability in a specific situation. This sentence is grammatically correct.
Can vs. May: Comparison Table
| Use | Can | May |
|---|---|---|
| Ability | ✔ Yes | ✘ No |
| Permission | ✔ Informal | ✔ Formal / Polite |
| Possibility | ⚠️ Sometimes | ✔ Common |
Common Mistakes
- ❌ She may swim very well.
✔ She can swim very well. - ❌ May you help me? (informal context)
✔ Can you help me? - ❌ She can not be able to attend.
✔ She may not be able to attend.
Last Updated on January 14, 2026
