Is "could've" or "should've" standard English?

Question

As the title says — is "could've" or "should've" standard English or is it slang and should correctly be spelled "could have" and "should have"?

Answer 1

It is standard English, not slang; yet in certain contexts the contractions should not be used. I wouldn't use "wouldn't" in a college-level essay, for example. It is informal.

Answer 2

Yes, they are both standard English. What I think you're asking about is formality; "could've" and "should've" are contractions of "could have" and "should have," respectively. Contractions should not be used in formal writing. Otherwise, they are acceptable variations of standard English that can be used in informal writing and everyday informal speech.