The ideal daypack for hiking depends on the user and the type of hike. Daypacks can vary in size and capacity. The capacity is typically measured in liters. For a one-day hike, a pack between 15 to 30 litres will typically suffice. However, if one is planning on traveling a greater distance or is undertaking a trail that requires varying equipment or weather conditions, a pack in the 30 to 40 liter range will accommodate more gear and food.