…it is OK to use a preposition at the end of a sentence!
Somewhere deep within all of us there lurks a “grammar bully” — the stern guardian of the language who will never let us forget a comma or allow us to meander into a run-on sentence. She means well, but sometimes you need to tell her where to get off.
If it were up to her, we would never end a sentence with a preposition, such as at, off, with or for. Instead, we’d be twisting our words into tortured phrases to avoid it and we’d all be the worse for it. It’s time to quell the grammar bully on this subject and to do what makes sense. As Winston Churchill reportedly said when someone rewrote his words to correct his use of a preposition at the end of a sentence: “This is the sort of bloody nonsense up with which I will not put.” Happily, none of us have to put up with it. Despite what your grammar bully is telling you, it is generally fine, and sometimes preferable, to end a sentence with a preposition.
The original rule was derived from a Latin linguistic prescription to end a sentence with a strong word, and while that is good advice, you don’t have to go to extremes. A preposition at the end of a sentence is acceptable if it helps you to avoid an awkward sounding and poorly constructed sentence.
“Which table did you eat at,” sounds better to Americans than “At which table did you eat?” “He gave the audience the performance for which it longed,” is not better than “He gave the audience the performance it longed for.” If you say, “At what are you driving?” instead of “What are you driving at?” you’ll avoid the preposition at the end of the sentences, but all your friends will think you’re weird.
There is a time when you shouldn’t use a preposition at the end of sentence and that is when you don’t need to. If the sentence makes sense without the preposition leave it off. “Where will you be meeting her at?” is wrong, not because it ends in a preposition, but because the preposition is not necessary.