Choose a hiking backpack by matching volume to trip length and total load, then dial in the fit by torso length and hip size with real weight in the pack.
Picking a backpack goes sideways fast when you shop by height or looks. The right process runs in one direction: decide what trips you’ll take, work out your torso length and hip circumference, load the pack with real gear, and walk around before you commit. A pack that rides on your hips turns a 10-mile day into a pleasure; the wrong one turns the same trail into regret. The table below maps volume to trip length so you can start with the right size range, then we’ll cover measuring, testing, and common mistakes.
What Size Backpack Do You Need For Your Trip?
Volume is measured in liters. REI notes most backpacking packs start around 45 liters and range up to 80 liters, while the Appalachian Mountain Club gives 40–55 liters for a weekend, 55–70 liters for a week, and 70–90 liters for expeditions and winter trips.
| Trip Type | Volume Range | Best For |
|---|---|---|
| Day hikes | 18–40 L | Water, snacks, layers, first-aid kit |
| Multi-day hikes | 35–50 L | Light overnighters with minimal gear |
| Weekend backpacking | 40–55 L | Two nights out with a standard kit |
| Week-long trips | 55–70 L | Five to seven days of food and gear |
| Expeditions / winter | 70–90 L | Bulky cold-weather gear, ropes, group loads |
Treat liters as a starting point, not a law. A 50–55 liter pack is a practical sweet spot for many multi-day trekkers, but your gear weight matters more. If you’ve lightened your kit with a down sleeping bag and compact tent, drop a size class; if you carry heavier gear, bump up.
How To Measure Torso Length And Hip Size Correctly
Sizing comes down to torso length and hip circumference, never height. The American Hiking Society and REI both point to the C7 vertebra—the bony bump at the base of your neck—as the start. Measure from there down to the line between the tops of your hip bones, with a second person’s help so the tape stays straight. The hip belt should sit over your iliac crest, the top ridge of your hip bones. If the belt rides up, slips down, or can’t tighten snugly, the size is wrong. Every brand sizes slightly differently, so check the manufacturer’s chart for the specific model. Two people of the same height can differ by several torso sizes; a pack built for a taller torso will ride low and dump weight on your shoulders all day.
How To Test A Pack With Real Weight Before Buying
An empty pack tells you almost nothing. Load it with your actual gear or at least 15 pounds and wear it around the store or house. The American Hiking Society recommends walking, bending, and reaching to simulate real movement. Once loaded, tighten the hip belt first so it sits on your pelvis, then adjust shoulder straps, sternum strap, and load lifters in that order. When it’s right, the pack won’t wiggle, and most weight rides on your hips. If your shoulders ache in the first few minutes, the hip belt isn’t transferring weight properly. That transfer is the whole game: 75–80% of pack weight should ride on your hips. Once your load climbs past 15–20 pounds, a framed pack is the right call because the frame shifts weight to your hips; skip frameless options for overnight trips above that weight.
What Features Actually Matter For Your Hiking Style
Features follow use, not fashion. A sleeping-bag compartment at the bottom keeps your sleep system accessible, a rain cover protects gear in a downpour, and side pockets put water within reach. Ventilation matters on hot, humid trails—a trampoline-style back panel keeps your spine drier but pushes the load farther out. Weigh durability against pack weight: a 50–60 liter pack around 4 pounds is a strong middle ground for rocky trails without an extra pound. For tested budget options, see our roundup of the best budget hiking backpacks.
FAQs
Should I size a hiking backpack by my height?
No. Height alone is a poor predictor of fit because torso length varies widely. Measure from the C7 vertebra at the base of your neck to the line between your hip bones, then match that number to the manufacturer’s chart for the specific model.
How much weight should the hip belt carry?
Roughly 75–80% of the pack’s total weight should rest on your hips, not your shoulders. Once your load exceeds 15–20 pounds, a framed pack improves transfer. If you feel shoulder strain early in a test wear, the hip belt fit is wrong.
Is a 50-liter backpack big enough for a week-long trip?
It depends on your gear. Week-long trips typically need 55–70 liters, but with a compact tent and down sleeping bag, a 50–55 liter pack can work. Test with your actual gear loaded before ruling a size in or out.
References & Sources
- REI. “How to Choose a Backpack.” Covers volume ranges, torso measurement, and fitting guidance.
- Appalachian Mountain Club. “How to Choose the Right Backpacking Pack.” Details volume ranges by trip length and load-bearing guidance.
- American Hiking Society. “Backpacks: Fit and Features.” Explains torso measurement and hip-belt placement principles.
- FitlyFast. “Best Budget Hiking Backpacks.” Tested roundup of affordable pack options.