The terms all together and altogether can be confusing in English. Once you’ve read through this lesson, you’ll have an altogether better understanding of them.
All together means everyone or everything together.
If the two terms can be separated, that’s a dead giveaway that the term you want is all together.
Altogether is an adverb and means "all in all," "all told," or "completely."
The Bottom Line
If you can replace the term with something like "completely" or "when all is said and done," you are altogether better off with altogether. If you can rewrite the sentence to use all and together separately, the term you want is all together.