Should Have, Could Have, Would Have

Level B2 · Modals

should have, could have, and would have all use modal + have + past participle to talk about the past, but for a different reason than certainty (see Modals of Deduction) — here they express regret, criticism, or an unrealized possibility, not what actually happened.

Each modal marks a different kind of unrealized past:

• should have + past participle = a past action that didn't happen but would have been the right one: You should have called me (you didn't call, and that was a mistake).
• could have + past participle = something was possible but didn't happen: I could have helped you (I had the ability/opportunity, but I didn't).
• would have + past participle = the result side of an unreal past condition (see third conditionals), or a plan that didn't happen: I would have come, but I was ill.

Match the modal to what it expresses about the unrealized past:

• should have/shouldn't have + past participle = regret or criticism about a past action (or its absence): You should have told me sooner; She shouldn't have shouted at him.
• could have + past participle = an unused ability, opportunity, or possibility: I could have won, but I got nervous; He could have called an ambulance.
• would have + past participle = usually the consequence half of a third conditional, or an intention that didn't happen: If I'd known, I would have come; I would have called, but my phone died.
• All three keep have unstressed and often contracted in speech (should've, could've, would've) — but in writing, of is never correct here: should of gone is a common spelling mistake for should have gone.

The most common mistake is writing of instead of have — should of, could of, would of are all wrong; they come from how the contraction should've sounds, not from actual grammar. The full, correct form is always should/could/would + have + past participle. A second frequent error: confusing should have (regret about a wrong past action) with must have (near-certainty about what happened) — You should have locked the door means you didn't lock it and that was a mistake, while You must have locked the door means I'm sure you did lock it.

Look for should have/could have/would have (or their contractions) signalling regret, criticism, unused ability, or an unrealized plan — and double-check that of never appears where have belongs.

Practice

Should Have, Could Have, Would Have · Should Have vs Must Have & Mixed Practice