- The most important measurement when it comes to sizing backpacks is the torso measurement. In order to get the correct measurement, it will help to have someone else work the measuring tape for you while you stand up straight. Stand flat on your feet with your back straight and your eyes straightforward. Have the person measuring begin at the C7 vertebra, which is the bump you'll feel on the base of your neck. If you have any trouble, bend your head forward so the C7 will protrude more prominently, but keep your head straight when taking the measurement. Put your hands on your sides around the top of your hips so that your thumbs extend in a straight line perpendicular to the top of your hips. This area is known as your iliac crest. Measure down to the area between your thumbs. Record the measurement in inches.
- Refer to the sizing guide for the specific backpack that you plan to purchase and find your size. If the backpack uses small, medium and large, refer to the conversion chart to find the correct size for your torso measurement.
- While numeric sizes can help you order a backpack online, it's always best to fit the pack in person to ensure that it is both correctly sized and comfortable. This is especially true if you fall between sizes. To get the best idea of fit, put a little weight, about 10 to 20 pounds, in the backpack. Loosen all straps and then put the pack over your shoulders. Close and tighten the hip belt from both sides so that it is snug. It should sit comfortably on top of your hips and extend an inch above and below the iliac crest. Tighten the shoulder straps, then the load-adjustment straps on top. The load straps should be at about a 45-degree angle between your shoulders and the backpack. Adjust, tighten and close the sternum strap. Adjust the load stabilizers on the bottom of the shoulder straps. Finally, fine-tune the shoulder-strap adjustment so that it is as comfortable as possible.
- Ensure that the backpack fits correctly and provides the comfort that you're looking for. The hip belt should be snug and sit squarely on your hips. All straps should be flush against the body without leaving any gaps. The shoulder straps should feel comfortable and should be wide/narrow enough for your shoulders. Give a test walk in the backpack and compare it with other models to find one that best suits you.
