Selecting the right backpack and getting the correct size of pack for your body type and composition, is both important and necessary, if you are going to get the most enjoyment from your outdoor adventures. Not only should you make an effort to obtain the correct size of backpack, I recommend that before making a purchase, you do your research on the type of backpack to obtain that will suit your needs and allow your outdoor activites to progress and grow in the future. I also feel that to get the best results, you should try on the backpack and utilize weight during in the backpack during the selection process to mimic the feel on the trail when loaded.
A quick and easy way to size yourself for a backpack is to measure the length of your torso. This is completed by measuring your back along the spine from your iliac crest (the top of your hipbones) to your C-7 vertebra (the knobby bone at the base of your neck). This process is much easy and more accurate if you have a friend help.
The C7 vertebra is easily found by leaning your neck forward, causing it to protroud slighty. The iliac crest can be located by simply following the spine down to the top of the pelvis area, in the middle of your hip bones. Once you have found these two areas, measure this distance to obtain your torso length. I have included a chart that contains various torso lengths and the corresponding backpack suspension size. I would also recommend that you check this sizing with the individual backpack manufacturer you plan to purchase from to ensure the correct sizing.
|Torso Length||Suspension Size|
|Under 18 in (45 cm)||Small|
|18 to 20 in (45 to 50 cm)||Medium|
|21 in (52 cm) and over||Large|
To determine your hip belt size, measure around your hips, not your waist. A properly fitted hipbelt rides centered over the hipbones and needs to be very snug. The padded portion should wrap well around your hips, leaving a gap of 3 to 6 inches between the tips of the pads when securely tightened.
Harness sizing usually corresponds to pack size, when you try on your backpack the harness should terminate 2 to 3″ beneath the armpit and the webbing should not touch the body. Most backpacks allow you to adjust the harness up and down the backpanel, thus allowing the torso length to be adjusted up to 3″.
Once you have selected the correct size backpack, before you make a purchase, it’s time to put some weight in the pack, 20 to 30 pounds of well distributed weight will serve this purpose. Tighten down the hipbelt and harness, connect the sternum strap and position it about 2 inches below your collarbones and tighten it down lightly. Lastly, tighten the load lifter straps to draw the load against your back. In a good fit, there should be no pressure points and no gaps between your body and the pack.