Teacher Discussion Forums

Could you tell me if "That's all for the best" is roughly the same as "It's an advantage under the circumstances" or "It's finished happily in spite of everything"

Only if by roughly you mean super-coarse grit sandpaper.
"It's all for the best" is usually used where sth bad happened that replaced sth that the speaker perceives as even worse. Sb might say it, for instance, after the death of sb suffering from an extremely painful and debilitating illness.

Thank you

Examples from learner dictionaries:

LDOCE4 online: 13 be for the best especially spoken used to say that a particular event may seem bad now, but might have a good result later: I still don't want him to go but maybe it's for the best.

OALDCE7 online: be (all) for the best used to say that although sth appears bad or unpleasant now, it will be good in the end: I don’t want you to leave, but perhaps it’s for the best.

CALD online: for the best
If an action is for the best, it is done to improve a situation or produce a good result, although it might seem unpleasant at the time:
Ending a relationship is always hard but in this case it's definitely for the best.

Similar context in all 3 dictionaries!

By the way, Gabriel, take close note of the exact wording of phrases you meet, and don't use definitionese or paraphrase in place of, or in preference to, genuine attested phrases - just wondering where you got your three above phrases from, is all.

I got the phrases from a multiple choice exercise.