If you're planning a backpacking trip, you'll need to map out how much distance you expect to cover in a day. This distance will be different for each person, and a number of things will factor into the total -- your fitness level, the weight of your pack, the terrain and the condition of your traveling companions. A good average distance is 10 miles (16 kilometers) per day. Traveling with children can cut that average in half. When planning your trip, you should also take zero days into account. Zero days is the term used for days that are spent in camp, with no hiking.
You might, for example, schedule in a zero day to rinse out laundry and rest at a nicer campsite. You also need to account for unplanned zero days -- when you have to spend a day hunkered down in your tent riding out a thunderstorm, for example. For your first backpacking trips that are more than a few days duration, plan on a zero day every few days to rest and recharge.
Many maps provide an estimate on how long it takes to hike a particular trail. This can be helpful when you're planning your journey. You want to make sure you arrive at a suitable campground at a suitable time, especially if you're counting on that campsite's water source. And you want to arrive at camp early enough to set up your tent before dark.
The less experience you have backpacking, the more important it is to carefully choose your destination each evening. If you must make the choice between a short day and a long day, choose a short day. Pre-trip, you may feel you can cover 10 miles each day, but you may wish you'd planned less aggressively once you're out on the trail.
Regardless of how many miles you plan on covering each day, leave plenty of time for setting up camp. This chore is much more enjoyable and goes much quicker in the daylight. Remember, setting up camp is more involved than simply pitching a tent. And the longer you're out, the more there is to do. You'll need to locate a water source and replenish your supply, lay out your sleeping mat and bag, prepare a meal to refuel from the day's trip and hang up anything that has gotten wet from rain or perspiration so that it'll be ready to use the next day. It may be tempting to avoid these chores when you're tired from hiking, but you'll sleep much better after eating a hot meal, and your morning will go much smoother if you arrange your camp carefully when you arrive.
You'll also need to plan for the weather. When you're hiking in hot weather, water becomes even more important. Not only is it important that you stay hydrated, but you've got to gather enough water for your day. The water in streams and rivers may dry up during summer months. If you plan on hiking during hot weather, ask other experienced hikers whether the water sources featured on maps are really available year round.
Cold weather hiking arguably is even more of a challenge. It requires a greater level of physical fitness because your backpack will most likely be heavier -- you'll need to pack more warm clothing and more food. The body heats itself through calories, so backpacking in cold weather demands more of them. Without enough food, you won't have the energy to complete your hike.