Modals of Possibility: Could, May, Might

Modals of possibility are auxiliary verbs that express the speaker's or writer's degree of certainty or uncertainty about the likelihood of an event or situation.

They are used to indicate the possibility, probability, or impossibility of something happening or being true. The three most common modals of possibility in English are 'could', 'may', and 'might'.

Grammar Structure

Check out the main modal verbs page for the detailed grammar of this type of verb, but this is key the structure of these modals in affirmative sentences:

Present & Future

Subject + could/may/might + base verb (infinitive form without 'to')

We could stay at home instead of going out.
It may rain later, so bring an umbrella.
They keys might be in the car.

Past

Subject + could/may/might + have + past participle

I could have gone to the party, but I was too tired.
She may have already left for the airport.
He might have missed the train, so we should wait for him.

They can of course also be made negative (e.g. It may not rain later) or turned into questions (e.g. Could we stay at home instead of going out?).

Examples and Explanations

Now let's look in turn at these modals of possibility with examples.

The Modal 'could' for Possibility

The modal 'could' is used to indicate the possibility of an event or situation happening. Though it is seen as a past form of the modal 'can', it can be used to talk about possibilities in the present and future.

When used for the past (with 'have + past participle') it is used to talk about an event or situation in the past that was possible or could have happened but did not happen.

Present & Future

I could go to the concert if I finish my work in time.
She could be late because of the traffic.
Could we stay at home instead of going out?

Past

They could have passed the test, but they didn't study hard enough.
They could have got the train if they had left earlier.
Do you think she could have won the competition if she had practiced more?

The Modal 'may' for Possibility

The modal 'may' is used to express the possibility or uncertainty of an event or situation happening. Specifically it's about an event or situation for which there is no confirmation or evidence to confirm it for definite.

It tends to be formal in nature and is commonly found in writing rather than conversation. These are some formal examples.

Present & Future

In light of recent market trends, the company may need to adjust its investment strategy.
The CEO may be able to attend the shareholders' meeting next month.
The proposed regulations may have a significant impact on the industry.
The new technology may allow for more efficient production processes.
Based on current projections, the project may be completed ahead of schedule.

Past

The suspect may have been in the vicinity of the crime scene at the time of the incident.
The report suggests that the error may have occurred during the data collection phase.
The company may have missed out on potential opportunities by not pursuing the partnership.
It is possible that the delay in delivery may have been due to unforeseen circumstances.
The product may have been recalled due to safety concerns.*

*The last one is in passive voice

The Modal 'might' for Possibility

The modal 'might' is used to express a lower degree of possibility or uncertainty compared to 'may' or 'could'. It's used more for informal situations than 'may'.

Present & Future

I might go to the gym after work today.
The weather might not improve by the weekend.
The new employee might need some additional training to meet the job requirements.
Might the meeting be rescheduled due to scheduling conflicts?
The company might consider expanding into international markets in the future.

Past

Do you think she might have left her phone at the office yesterday?
The party might have been more enjoyable if more people had attended.
The flight might not have been delayed if it there was no storm.
The restaurant might have run out of the dish I wanted to order.
The candidate might have been more qualified than the one who was ultimately selected.