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

Choose a hiking backpack by matching capacity to trip length, measuring your torso instead of your height, and picking an internal frame with a hip belt that transfers 75–80% of the weight to your hips.

Nothing ruins a hike faster than a pack that doesn’t fit. A too-large bag tempts you to overpack, while a mismatched torso length leaves the load hanging off your shoulders instead of your hips — a fast track to back pain. The fix comes down to three decisions: capacity, fit, and frame type. Here is what matters for each.

Capacity: Match Liters to Your Trip

Backpack volume is measured in liters, and the right range depends entirely on how many nights you are out.

A useful rule: hikers tend to fill whatever pack they carry, so calculate your gear volume first, then buy a pack just large enough. Oversizing adds unnecessary weight and encourages overpacking.

Fit: Torso Length, Not Height

The most common sizing mistake is picking a pack by height. What actually matters is torso length — the distance from the C7 vertebra (the bony bump at the base of your neck) to the iliac crest (the top of your hip bones). Measure this span and match it to the pack’s sizing chart. Hip circumference also matters: measure at the top of the hip crests, then adjust the hip belt to sit right on those bones. Most brands offer packs in multiple torso sizes, and REI’s expert guide to backpack fit walks through the full measuring process.

Frame and Load: When Internal Frames Matter

For any load over 15–20 pounds, a frame is essential. Without one, the pack cannot transfer weight to your hips and all of it stays on your shoulders. Internal frame packs dominate the US market for loads up to about 50 pounds; they hug your back well and let you move through uneven terrain. Load categories break down roughly as ultralight (10–30 lbs), standard (20–40 lbs), and expedition (40–70+ lbs).

If your typical carry is under 25 pounds for a day hike, a frame is optional; for anything heavier, commit to an internal frame with a padded hip belt, sternum strap, and load lifters. Pack heavy items — stove, food, water — closest to your spine in the middle zone, light bulky gear like a sleeping bag at the bottom, and rain gear or snacks on top for quick access.

Once you know your size range, exploring specific models is the next step. Our curated roundup of budget-friendly hiking backpacks covers tested options that balance weight, capacity, and price.

FAQs

Should I size up or down if my torso length falls between two sizes?

Size down. A slightly smaller pack can be adjusted with load lifters and hip belt positioning, while a pack that is too large will never fit your spine properly and will sag the load onto your shoulders.

Do I need a hydration sleeve in my pack?

Not strictly, but it is a strong convenience feature. A hydration sleeve with a pass-through port lets you drink without stopping to access a side pocket. If the pack lacks one, you can still carry a bladder in the main compartment — though refilling becomes a hassle.

How much should my full pack weigh?

A good starting target for a weekend trip is 30–35 pounds total, including food and water.