My experience is that most backpackers will be satisfied with 2,250 to 2,750 calories per day.
If you are young, muscular, larger in size, and/or on an intense trip, aim for the high end of this range. If you are the opposite of any of those aim for the low end of this range.
Calorie-counting is tedious, so you may find it more practical to weigh your food. In this case, aim for 18 to 22 ounces of food per day.
The average caloric density of your food is generally about 125 calories per ounce, so 18 ounces equals 2,250 calories and 22 ounces equals 2,750 calories. …Food-Planning Basics for Backpacking