May vs. Can

Both can and may can be used to talk about possibility. But there is some difference between them. Can is used to talk about theoretical possibility; may is used to talk about factual possibility.

  • The road may be blocked due to the procession. (Factual possibility.)
  • Any road can be blocked. (Theoretical possibility – It is possible to block any road.)
  • There may be a strike next week. (It is possible that there will be a strike next week.)
  • Strikes can happen any time. (It is possible for strikes to happen any time.)
  • If you drive carelessly, you may have an accident. (Factual possibility)
  • Accidents can happen any time. (Theoretical possibility)

When we talk about possibility, could often means the same as may or might.

  • You may/might/could be right.

May not and Cannot

May not suggests improbability. Cannot suggests impossibility.


  • We may not go camping this summer. (= It is possible that we may not go camping.)
  • We cannot go camping this summer. (= It is not possible for us to go camping this summer.)

Manjusha Nambiar

Hi, I am Manjusha. This is my blog where I give English grammar lessons and worksheets.

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