Third Conditional in English: Form, Uses, Examples and Exercises

Third conditional in English is used to talk about unreal past situations and their imagined results. In other words, we use it to imagine how the past could have been different. This structure is very useful when we talk about regrets, criticism, missed opportunities or imagined past results.

We use the third conditional to talk about a past situation that did not happen, and to imagine what the result would have been if things had been different.

• I could have got into that dress if I had not eaten so much.
  (But I did eat too much, so I could not get into the dress.)
• If he had realised the traffic light was red, he would have stopped.
  (But he did not realise it, so he did not stop.)

Here is the basic structure of the third conditional in English:

If + past perfect, would have + past participle

• If I had studied more, I would have passed the exam.

We can also use:

• could have + past participle
• might have + past participle

Examples:

• If we had not been busy last night, we could have joined you for dinner.
• If Martin had written that email, he might have used more courteous phrases.

When Do We Use the Third Conditional?

1. To talk about past regrets

• If I had gone to bed earlier, I would not have been so tired.

2. To talk about missed opportunities

• If he had applied for the job, he might have got it.

3. To imagine a different past result

• If the weather had been better, we would have gone to the beach.

4. To criticise past actions

• If you had been more careful, you would not have broken it.

Third Conditional with Would, Could and Might

Would have

Use would have for a certain imagined result.

• If I had known, I would have helped.

Could have

Use could have for ability or possibility.

• If we had had more time, we could have visited the museum.

Might have

Use might have for a less certain result.

• If he had seen the message, he might have replied.

Third Conditional vs Second Conditional

We use the second conditional for unreal or imaginary situations in the present or future.

If + past simple, would + base verb

• If you learned more, you could pass that exam.
  (You still have a chance. The situation is present or future.)

We use the third conditional for unreal situations in the past.

If + past perfect, would have + past participle

• If you had learned more, you could have passed that exam.
  (The exam is finished. The situation is entirely in the past.)

To sum up, we use the third conditional in English to talk about unreal past situations and their imagined results.

Remember the formula:

If + past perfect, would have + past participle

• If I had known, I would have told you.

FAQ: 

What is the third conditional?

The third conditional is a grammar structure used to talk about unreal or imaginary situations in the past and their imagined results.

What is the form of the third conditional?

The form is:

if + past perfect, would have + past participle

Can I use would have after if?

No. This is a common mistake.

Incorrect: If I would have known, I would have called you.

Correct: If I had known, I would have called you.

What is the difference between the second and third conditional?

The second conditional talks about unreal present or future situations. The third conditional talks about unreal past situations.

Can I use could have and might have in the third conditional?

Yes.

• could have shows possibility or ability
• might have shows a less certain result

Download Third Conditional Practice Worksheet in PDF here

Related posts:

• Conditionals in English 
• Talking About Unreal Situations in English 
• If and Wish in English 
• Hypothetical Language in English 
• Alternatives to “IF” in English 

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