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2800ci is a lot of room for a "daypack".I would recommend getting all of the gear together that you would normally pack on a day trip. Find a couple different sizes of shoe boxes and see which one will hold all of your gear tightly. Measure that box to find out how many cubic inches it is. Then add 25% to that number to allow for unknowns (weather/different game) and you should have a good idea of how many cubic inches you need for a daypack.Disclaimer: These are only my opinions and have been found to be wrong on a number of occasions.