Use

The third conditional is used when talking about a possible result of something that did not actually happen in the past.

Example:

If I had gone to the party, I would have seen her.

Explanation:

The third conditional is used here because you went to the party, but I did not, so we did not see each other. If I had gone is the ‘if’ clause, and I would have seen is the main clause.

How to build

A third conditional sentence has an ‘if’ clause and a main clause. Clause can come first, but when the ‘if’ clause comes first we use a comma.

If + past perfect + would (not) have + past participle

• If I had known the film had such high ratings, I would have watched it.

• If I had known the film had such low ratings, I would not have watched it.

would (not) have + past participle + if + past perfect

• I would have attended the meeting if you had told me it was obligatory.

• I would not have attended the meeting if you had told me it was voluntary.

More Examples

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

• We would have gone to the park if it hadn’t rained.