What is the maximum single dose of xanax (alprazolam)?

It depends. It varies by your tolerance. You should not exceed. 4mg/24 hours as a general rule.
It depends. The physician drug reference shows that 4 mg. Is the maximum allowed dose . However, i must advise you strongly to use this drug cautiously as it can cause psychological addiction. It should only be used for a short term. A single dose of 1 mg. Is the usual dose with 4 mg. Maximum in 24 hours. The age, size and the severity of anxiety factors in the dosing.