and I can't find a specific comparison.
If it's any help A levels gain grades A-E as passes, plus N (close fail) and U (total fail).
My advice would be to contact the admissions office of the university - I know from my alma mater that U.S. students are usually very welcome (you pay higher fees than we locals do), and a speculative e-mail is likely to receive a full response. But, sounding a note of caution, this is not a good time of year - A level results have just been published and they're in the midst of the annual scramble to sort out folk who didn't get the requirements (it's called clearing), so if you're not trying to enter this acadmic year - it might be worth waiting until September.
F.Y.I. the overseas students page of my beloved former university:
http://www.st-andrews.ac.uk/services/admissions/UGOSStu.htmYou might also want to contact UKCOSA the Council for International Education:
http://www.ukcosa.org.uk/If you do come over here to study - I hope that you have a great time. :hi: