That depends on YOU. All hikers are different, and there are so many variables like your personal condition and experience, weight of your pack, how good your boots are, how early you get up and start hiking and how late you hike in the day, etc. etc. Many hikers, especially those new to the sport, tend to try to hike too many miles in a single day. The result is very sore feet, muscles and bones, and an unpleasant hiking experience. It is best to start off with fewer miles per day and work up to longer miles as you gain experience.