Half Dome Trail has only one trailhead, so you'll be hiking it in and back out. Now, this is roughly a 1.5-day trek, so better have big a backpack to fit all the stuff you need. Now this trail is pretty long, so make sure you bring plenty of supplies. Half Dome Trail is 11.6 miles long; it's a long backpacking trail. This backpacking trail goes through some very different elevations, and that means that some parts of the backpacking trail could be very different from other parts of it. Sometimes this trail gets really dry, so make sure you check current conditions and fire restrictions with local forest authorities before you head out. The total elevation difference for Half Dome Trail is 5,142 feet which is a higher than average number.