You should count on this hike taking about 4 hours, but you never know stuff could go wrong and you could get stuck so be prepared for that. The total elevation difference for Nelson Flat Trail is 697 feet which is lower than average. This hiking trail is not that long but it's always good to bring some emergency supplies, you never know what could happen. You spend the whole hike in roughly the same elevation zone which means the conditions are about the same from start to finish. Sometimes this hiking trail gets really dry, so do check for current fire restrictions before you go if you plan to bring a stove or make a camp fire. Nelson Flat Trail is a one trailhead backcountry trail, so in and out is the way to trek it normally. With its 4.6 miles of walking distance it's a mid length hike.