Written English contracts occasionally. Spoken English contracts almost constantly, and many contractions never appear in writing at all.

The standard ones

  • I am → I'm | you are → you're | it is → it's
  • do not → don't | cannot → can't | will not → won't
  • I have → I've | he has → he's | we had → we'd
  • I would → I'd | they will → they'll

The ambiguous ones

Some contractions collapse two different words, and only context separates them:

  • he's = he is or he has
  • I'd = I would or I had
  • they're vs their vs there — identical in speech

Spoken-only contractions

These are normal in speech and should not appear in professional writing:

  • going to → gonna
  • want to → wanna
  • got to → gotta
  • kind of → kinda
  • let me → lemme
  • give me → gimme

You need to understand all of these. You never need to produce them.

Double contractions

Common in speech, rarely written:

  • "shouldn't've" — should not have
  • "couldn't've" — could not have
  • "I'd've" — I would have

When not to contract

  • Formal writing — contracts, policies, legal documents
  • When emphasising: "I am not going" carries more weight than "I'm not going"
  • At the end of a sentence — you cannot say "Yes, I'm." It must be "Yes, I am."
That last rule is a real trap. "Are you coming?" — "Yes, I am." Never "Yes, I'm."