How to Choose a Backpack for Hiking? | Fit, Size & Features

Most hikers buy the wrong pack because they measure height instead of torso. The number on the tag matters less than how the weight sits on your hips. Here is how to get all three decisions right.

Match Backpack Capacity to Your Trip Length

Capacity follows trip duration, not how strong you are. The ranges below reflect how much gear a typical overnight or multi-day trip actually demands.

• 20–50 liters: Day hikes and overnight trips where you carry minimal gear.
• 50–60 liters: Weekend trips with a tent, sleeping bag, and food.
• 60–80 liters: Multi-day trips with more clothing, food, and gear.
• 80+ liters: Extended trips, winter expeditions, or hauling gear for others.

Season matters as much as days. Three days in summer fit in a 50-liter pack; the same trip in shoulder-season with a bulkier sleeping bag and extra layers might push you to 60 liters. Buying extra volume “just in case” is a common mistake — a larger pack tempts you to carry weight you never needed in the first place.

Measure Torso Length, Not Overall Height

Your torso length determines which pack size fits, and it has little to do with how tall you are. Two hikers of identical height can need different sizes entirely. The measurement is simple to take at home with a flexible tape measure.

1. Find the C7 vertebra — the prominent bone at the base of your neck where the neck meets the shoulders. Tilt your head forward; it’s the bump that moves.
2. Place one hand on your hip so your thumb points back; that line across the top of your hip bones is the iliac crest, the shelf your hipbelt will sit on.
3. Measure straight down your spine from the C7 vertebra to that line across the iliac crests.

Compare that number to the pack’s published size range. Common ranges include SM, MD, LG, S/M, M/L, and XL, but the exact torso measurements for each size vary by model line, so always check the specific pack’s chart. A 16-inch torso can be a small in one brand and a medium in another — the letters matter less than your number inside that chart.

Hipbelt fit follows the same logic. Measure around your hips at the iliac crest, not your waist — those are different circumferences for most people. The padded belt should wrap fully around your hip bones, with the padding covering the crests rather than hovering above or below them.

What To Look For In A Pack’s Features

Features should serve the kind of hiking you actually do, not the full catalog of every option available. The right pack for a weekend hut-to-hut trip looks different from one built for off-trail navigation or summit days.

• Hydration compatibility: A sleeve and hose port matter if you drink on the move; verify the pack fits your reservoir size.
• Ventilated back panel: A trampoline-style or channeled back keeps your spine cooler but adds weight and can push the load further from your body.
• Pockets and organization: Hipbelt pockets for snacks, a top pocket for small items, and side pockets for bottles all speed up trail access.
• Attachment points: Trekking-pole loops, ice-axe holders, and daisy chains matter for technical routes but add nothing for a casual weekend.
• Removable day pack: Some overnight packs include a detachable summit pack — genuinely useful if you plan to set up camp and hike light from there.

Not every feature is universal. Hydration sleeves, ventilated panels, and attachment points vary by model, so verify what the specific pack includes before you buy rather than assuming.

Test The Fit Loaded, Then Decide

A backpacking pack is engineered to carry weight on your hips, and the only way to confirm it works is to load it and walk. Shoulder straps stabilize the load; they should not carry it. If you feel pressure on your shoulders after a few minutes with a loaded pack, the fit is wrong — either the torso size, the hipbelt, or the adjustment.

When you try a pack, add the weight you’d realistically carry and walk around for several minutes. Load transfer, hipbelt comfort, and how the pack moves with your body only reveal themselves under actual weight. The REI backpack fit and sizing guide covers the full measuring process and the adjustment sequence, and industry sizing pages from Osprey’s fit-and-size guide provide model-specific torso ranges so you can check your measurement against exact specs before ordering. For a field-tested starting point, our roundup of the best day hiking backpacks for women breaks down top picks by torso range and trial feedback.

Women’s-specific packs also use a differently shaped hipbelt and shoulder straps that angle around a narrower frame; if a pack pinches or gapes at the shoulders, try the other gender’s version before abandoning a model.

The Two Numbers That Decide Everything

Set your priority order before shopping: torso length first, then hipbelt circumference.