By Dana Okoro, Editorial Reviewer · Published September 14, 2026, 6:03 PM ET · Updated September 29, 2026, 6:16 PM ET
Direct Answer
Look for a pack sized to your torso length rather than height, a padded hipbelt meant to carry most of the load, a capacity matched to your typical trip length, and an adjustable suspension if you're still learning your fit. Ventilation, attachment points and pocket layout matter next.
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In plain English
Buying a backpack is a bit like buying shoes: the right fit matters more than any fancy feature. Packs come in sizes based on the length of your back, measured from the bony bump at the bottom of your neck to the top of your hip bones. A friend and a soft tape measure can get that number in a minute.
The padded belt around your hips is the most important part of a good hiking pack. It lets your legs, rather than your shoulders, do most of the work of carrying. After fit, think about how big a pack you need for the trips you actually take, and how much weight the pack is designed to carry. Pockets, mesh back panels and gear loops are nice extras, but they come after a pack that fits you and your trips.
The starting point for any hiking backpack is fit, not features: measure torso length from the C7 vertebra at the base of the neck to the iliac crest at the top of the hip bones, then match that number against a brand's own size chart rather than shopping by height.
Capacity by trip type
Trip type
Typical capacity
Day hikes
18–25L
Day hikes + first overnight
30–50L
Multi-day backpacking
45–55L
Fit and load-carrying features
Beyond size, a padded hipbelt matters most, since a correctly fitted one is meant to carry most of a loaded pack's weight off the shoulders. Look for a structured hipbelt on any pack expected to carry more than 15 pounds, and an adjustable torso-length suspension if you're not yet certain of your exact measurement. A ventilated back panel — mesh or channeled foam — reduces sweat buildup on warm hikes, and external attachment points for trekking poles or a sleeping pad add usefulness without adding much weight.
Frame type
An internal-frame pack, built around one or two aluminum stays or a semi-rigid framesheet, suits most hikers better than a frameless pack, since the frame keeps a load stable and transfers weight to the hipbelt even with imperfect packing. Frameless designs work well for loads under 10-15 pounds but offer little structure above that.
What not to prioritize first
Skip chasing the lightest possible pack or the newest fabric technology — Dyneema Composite Fabric, minimalist hardware and ounce-counting frame designs matter most to hikers who already know their gear list and base weight. A well-known mid-range pack from a brand like Osprey, Gregory, or REI Co-op, correctly sized and adjusted, outperforms an expensive ultralight pack that doesn't fit.
The 80% hipbelt figure, examined
A fitted hipbelt is often said to carry roughly 80% of the load. That matches some sources and not others. Big Agnes aims for about 80% on the hips,1 the Washington Trails Association says around 80%,2 and Alpkit gives a range of 60 to 80%.3 US Army doctrine, looking at 31 to 90 lb loads with a frame and hip belt, says about 30% is carried on the hips and lower back and 70% on the shoulders.4
Whatever the exact split, the direction of the advice is well supported. A study of load carriage found the hips tolerate pack pressure significantly better than the shoulders and recommended shifting load to the hips wherever possible,5 and a review of soldier load carriage says hip belts should be used whenever possible because they reduce shoulder pressure and increase comfort.6
Capacity bands and load ratings
WTA's capacity guide runs 25 to 30 liters for a full-day hike, 45 to 50 liters for one or two nights, 50 to 70 liters for 3 to 7 nights, and 70+ liters for large loads.2 The page's 18 to 25 liter day-hike band is smaller; both are reasonable, and the right answer depends on how much water and clothing your hikes demand.
Liters say nothing about weight, so check the load rating too. REI says its Flash 55 is comfortable with loads up to 35 lb,7 rates its Traverse 60 frame for up to 45 lb,8 and Gossamer Gear gives its Mariposa 60 a 30 lb comfort load and 35 lb maximum.9 REI notes frameless packs save weight but are much less comfortable under heavy loads.10 The page's 10 to 15 lb limit for frameless packs is a widely used rule of thumb rather than a sourced threshold.
Torso range and adjustable harnesses
Some guides say most adults measure 16 to 20 inches. That range isn't backed by a source in this site's library, and brand size runs suggest adults vary more widely: Granite Gear's three sizes span 15 to 24 inches,11 and Hyperlite offers its Southwest in five torso sizes from under 15 inches to 21+ inches.12 Hyperlite also stresses that height is not a reliable proxy for torso length.13
Adjustable harnesses help when you're unsure. Deuter's VariClick system, for example, offers five-stage back-length adjustment on Aircontact Core packs,14 yet Deuter still advises choosing even adjustable packs in the correct back length.15 Whatever you buy, Big Agnes suggests fitting it with 10 to 20 pounds loaded,1 since an empty pack hides fit problems.
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