Conditionals

The Third Conditional in English

Level B2 Conditionals
Key idea

Use the third conditional to talk about unreal situations in the past — things that did not actually happen. The structure is 'if' + past perfect, then 'would have' + past participle: "If I had known, I would have called." The speaker didn't know, so they didn't call. It's perfect for expressing regret, criticism, or how the past could have gone differently, as in "She would have passed if she'd studied" or "If we hadn't left late, we wouldn't have missed it."

Examples

  • If I had known, I would have called. the speaker didn't know, so didn't call
  • She would have passed if she'd studied. she didn't study, so she failed
  • If we hadn't left late, we wouldn't have missed it. leaving late caused missing it

The full lesson

Everything in the video, in text.

  1. The Third Conditional

    the past that never happened

    Want to talk about a past that never happened — the regrets, the what-ifs? There's one pattern for it, and one famous way to get it wrong.

  2. If + past perfect, would have + past participle.

    We use it for unreal situations in the past — things that did not happen, and the result that therefore never came. Here's the shape.

  3. The two halves

    if-clause
    • if + had
    • + past participle
    • the unreal condition
    result
    • would have
    • + past participle
    • the outcome that never was

    Two halves. The if-half sets the unreal condition with had plus a past participle. The result-half uses would have plus a past participle.

  4. If I had known, I would have called.

    unreal past

    Take the classic. If I had known, I would have called. I didn't know — so I didn't call. Both parts are firmly in the past.

  5. She would have passed if she had studied.

    result first

    The result can come first — no comma needed then. She would have passed if she had studied. She didn't study, so she failed.

  6. If we hadn't left late, we wouldn't have missed it.

    negative form

    It works with negatives too — a cause and an avoided result. If we hadn't left late, we wouldn't have missed it. Leaving late is exactly what caused us to miss it.

  7. Past perfect = the unreal cause. Would have = the result that never happened.

    Why these forms? The past perfect — had plus participle — signals the condition is over and unreal. Would have marks a result that never actually arrived.

  8. ✗ If I would have known… would have in the if-clause
    ✓ If I had known… past perfect in the if-clause

    Would have lives only in the result half — never after if.

    Now the famous trap. Never put would have in the if-half. It's not if I would have known — the if-half takes the past perfect: if I had known.

  9. Don't mix them up

    2nd — unreal present
    • If I knew, I would call.
    • now / general
    3rd — unreal past
    • If I had known, I would have called.
    • a finished past

    And don't confuse it with the second conditional. Second conditional is the unreal present: if I knew. Third conditional is the unreal past: if I had known.

  10. If I had saved more, I would have bought it.

    regret

    One more, for regret — its most common use. If I had saved more, I would have bought it. A finished past, looking back at what might have been.

  11. Remember

    • if + had + past participle
    • would have + past participle
    • never: if + would have

    So, to lock it in: if plus past perfect, then would have plus past participle. And would have never follows if.

Related lessons

The Zero Conditional in EnglishThe First Conditional: If + Present Simple, Will + Base VerbThe Second Conditional: 'If I won the lottery, I'd travel'