3 Features You Need in an Internal Frame Backpack

Internal frame backpacks are lightweight, easy to shoulder, and ideal for multi-day trips outside. (Teton Sports/)

The majority of backpacks on the market today are internal-frame packs. While external frame packs are still available, they are mostly confined to situations where the user is carrying very heavy loads, like an inflatable watercraft, expedition or research gear, or even full game bags. Internal bags have been the standard for decades now because they conform to your body, don’t have rigid external tubing that can hang up on obstacles, keep the load on your hips, and won’t throw you off balance on uneven terrain. Here are a few things to look for when shopping for an internal-frame pack.

Volume

Think about how many days you’ll be hiking, and the amount of gear you’ll need, to help you determine a proper pack size. (Teton Sports/)

The first consideration is pack capacity. Volume is measured either in cubic inches or, more commonly, in liters. Day hikers will get by with a pack in the 25- to 35-liter range. Backpackers striking out for one to three days will need a pack anywhere from about 30 to 50 liters. Trips of more than three days call for packs of 50 to 70 liters or larger. Pack volume is also a function of season. Winter demands that hikers carry more clothing, food, and fuel, so assess your seasonal hiking habits when considering volume.

Length and Girth

A properly fitted pack should displace the weight on your hips, not shoulders. (Osprey/)

The two most important dimensions when sizing a pack are your torso length (not your height) and waist size. Look for an adjustable suspension system, and make sure the pack allows the load to ride on your hips rather than your shoulders. Toward that end, a well-fitted and adequately padded waist belt can make all the difference in how well you are able to handle the load.

Functionality

Before you settle on a pack, make sure it has the features and compartments you need to organize gear. (Gregory/)

Modern internal packs are usually loaded with features. For anything longer than day hiking, a pack with a removable top compartment that can be used as a fanny pack makes short side treks more enjoyable. A separate sleeping bag compartment and stow-away rain fly that covers the entire pack are pretty standard. Of course, you want well-cushioned hip straps and lumbar supports, just make sure they don't come at the expense of ventilation along your spine. Other useful features include daisy chain loops on the pack's back wall; an internal hydration-bladder compartment; side zippers for accessing the entire pack without unloading it; and loops or other attachment points for lashing down water bottles, tools, and other accessories.