According to the number
On your own outing, you can choose 25~35 liters of backpack. Holidays with family children travel, from the perspective of caring for the family, the need to choose 40 liters of backpack, external systems to more than to help families carry umbrellas, cameras, food and other items.
According to gender
The choice of outdoor backpacks is not the same as men and women differ in their size and bearing gravity. General for a day or two short trips, men and women GM 30 liters of backpack can be. More than 2-3 days of long-distance travel or camping, to choose 45 to 70 liters or even larger backpacks, generally while men choose 55 liters of backpack, women choose 45 liters backpack.
According to itinerary
One-day trip, ride, mountaineering activities, select 30 liters of the following backpack. Two-Three days Camping can choose 30-40 liters of multi-functional backpack, 4th above hiking, to place tents, sleeping bags, moisture pads and other outdoor equipment, can choose more than 45 liters of backpack. In addition, the general field activities and climbing mountains of the backpack is different, climbing the backpack with no many parts, like climbing friends need to pay attention.
According to length
Before picking the backpack, first need to measure their rear upper body length, namely the cervical spine protrusion to the last section of the lumbar distance. If the trunk length is less than 45 cm, you should buy a small package. If the trunk length is between 45-52 cm, you should choose a medium size package. If your trunk is more than 52 cm long, you should pick a large package.