Backpack Size Calculator

Tilt your head forward and feel for the bony bump at the base of your neck (C7 vertebra). Have someone measure from that point down your spine to the top of your hip bones (iliac crest). This distance in inches is your torso length.

A 20–30 liter backpack is ideal for day hikes. It's enough for water, snacks, rain jacket, first aid kit, and a few extras without being cumbersome.

Torso length, not overall height, determines pack size. Two people of the same height can have very different torso lengths, so always measure your torso directly.