How to Choose a Backpack

Internal-frame backpacks: The majority of packs sold at REI today are body-hugging internal frame packs that are designed to keep a hiker stable on uneven, off-trail terrain. They may incorporate a variety of load-support technologies that all function to transfer the load to the hips.

External-frame backpacks: An external-frame pack may be an appropriate choice if you're carrying a heavy, irregular load, like toting an inflatable kayak to the lake. External frame packs also offer good ventilation and lots of gear organization options.

Frameless backpacks: Ultralight devotees who like to hike fast and light might choose a frameless pack or a climbing pack where the frame is removable for weight savings.

Some packs feature a suspended mesh back panel to combat the sweaty-back syndrome you tend to get with internal frame packs that ride against your back. Also called a “tension-mesh suspension,” this is a trampoline-like design where the frame-supported packbag rides along a few inches away from your back, which instead rests against the highly breathable mesh.

Ventilation "chimneys" that are built into back panels and promote airflow are another option meant to solve the same issue.

Top-loading openings are pretty standard. Items not needed until the end of the day go deep inside.

Panel access: Some packs also offer a zippered front panel which folds open exposing the full interior of the pack, or a side zipper, which also makes it easier to reach items deeper in your pack.

Elasticized side pockets: They lie flat when empty, but stretch out to hold a water bottle, tent poles or other loose objects

Hipbelt pockets: These accommodate small items you want to reach quickly — a smartphone, snacks, packets of energy gel, etc.

Shovel pockets: These are basically flaps stitched onto the front of a packbag with a buckle closure at the top. Originally intended to hold a snow shovel, they now pop up on many 3-season packs, serving as stash spots for a map, jacket or other loose, lightweight items.

Front pocket(s): Sometimes added to the exterior of a shovel pocket, these can hold smaller, less-bulky items.

Some packs are designed with a removal daypack that is perfect for day trips, summit hikes or supply runs during a thru-hike. Some packs have top lids that detach from the main pack and convert into a hipbelt pack for day trips.

This is a zippered stash spot near the bottom of a packbag. It's a useful feature if you don't want to use a stuff sack for your sleeping bag. Alternately, this space can hold other gear that you'd like to reach easily.

If you're using a lightweight pack with a fairly minimalistic hipbelt and lumbar pad, you can encounter sore spots on your hips and lower back. If this is the case for you, consider using a cushier hipbelt.

If you frequently travel with an ice axe or trekking poles, look for tool loops that allow you to attach them to the exterior of the pack. Rare is the pack that does not offer at least a pair of tool loops. You might also look for the following:

A daisy chain — a length of webbing stitched to the outside of a pack — to provide multiple gear loops for attaching a helmet or tools.

A reinforced crampon patch (to prevent crampon points from gouging holes in the packbag).

Gear loops on the hipbelt or low on the pack body, useful as clip-on points for gear or possibly as attachment points for skis.

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If you expect rain on your trip, this is a good item to carry. Pack fabric interiors are usually treated with a waterproof coating. Yet packs have seams and zippers where water can seep through, and the fabric's exterior absorbs some water weight during a downpour.

An alternative: bundling gear internally in waterproof "dry" stuff sacks. Lightweight dry sacks can be a better option in windy conditions; strong gusts have the potential to abruptly peel a cover right off a pack.

Nearly all packs offer an internal sleeve into which you can slip a hydration reservoir (almost always sold separately) plus 1 or 2 "hose portals" through which you can slip the sip tube.

Some packs are available in multiple sizes, from extra small to large, which fit a range of torso lengths. These ranges vary by manufacturer and by gender. Check the product specs tab for size details of a specific pack.

Other packs may feature an adjustable suspension, which can be modified to fit your torso, especially if you're in-between sizes. The drawback: An adjustable harness adds a little weight to a pack.

The majority of a backpack's weight, 80 percent or more, should be supported by your hips. Backpack hipbelts usually accommodate a wide range of hip sizes, from the mid-20 inches to the mid-40 inches. People with narrow waists sometimes find they cannot make a standard hipbelt tight enough and need a smaller size. Some packs offer interchangeable hipbelts, making it possible to swap out one size for another.

Because they have smaller frame sizes, women's backpacks often work well for young backpackers of either gender. Torso dimensions are generally shorter and narrower than men's packs. And hipbelts and shoulder straps are contoured with the female form in mind.

These typically offer smaller capacities and include an adjustable suspension to accommodate a child's growth. Women's backpacks, with their smaller frame sizes, often work well for young backpackers of either gender. So do small versions of some men's packs.