The half-life of Xanax is the time it takes for half of the drug to be eliminated from the body. The average half-life of Xanax is about 11 hours in healthy adults, but it can range from 6.3 to 26.9 hours depending on the person. After four to five half-lives, 97% of the drug has cleared from the body, and the drug is no longer considered to be having any effect. However, it is important to note that the half-life of Xanax can be affected by various factors such as age, weight, metabolism, and liver function. Therefore, it is difficult to determine exactly how long Xanax will last in a persons system. In general, Xanax will fully clear the body within two to four days for most people.