Properly fitting a backpack starts with measuring your torso length, not your height, the hipbelt carries the load.
The single biggest mistake in backpack fitting is buying by height. Your torso length — measured from the C7 vertebra at the base of your neck to your iliac crest (the top of your hip bones) — is what actually determines pack size. Fit the pack to your torso, and you’ll carry weight where it belongs: roughly 80% on your hips, 20% on your shoulders, and zero on top of your shoulders.
How to Measure Your Torso for a Backpack
GRAB A FRIEND and a soft tape measure — you can’t easily reach your own C7 vertebra. Tilt your head forward and feel for the bumpy bone at the base of your neck (C7). Then place your hands on your hips to find the top of your hip bones (iliac crest). Measure the distance between these two points; that number is your torso length. REI’s official guide and Gregory’s fit guide both use this method: locate C7, measure to the iliac crest, then compare to the manufacturer’s sizing chart. Don’t rely on height alone — two hikers of equal height can easily need different pack sizes.
The Proper Backpack Fit Sequence
THE RIGHT ORDER MATTERS. Loosen every strap completely before you start, then load the pack with 10–20 pounds (as REI and The North Face recommend) so you’re fitting under real conditions. Here’s the sequence that works:
- Position the hipbelt first. The padding should sit over and hug your iliac crest — The North Face says it should “straddle” the hip bones. The hipbelt carries most of the load.
- Tighten the hipbelt. Fasten it snugly so the pack’s weight transfers to your hips, not your shoulders.
- Adjust the shoulder straps. They should wrap closely around your shoulders and upper back without bearing significant weight. No gaps, no strain on the top of your shoulders.
- Tighten the load lifter straps. These should pull the pack closer to your back at roughly a 45-degree angle toward the pack body.
- Fasten the sternum strap. Buckle it so your shoulder straps stay in place and your arms move freely — not so tight that it restricts breathing.
Hipbelt and Shoulder Strap Positioning Details
AFTER THE SEQUENCE, check these four fit markers. First, the hipbelt should entirely cover your hipbones. If it sits too low or too high, you’ll feel it — a belt resting on top of your hip bones can restrict your diaphragm. Second, your shoulder straps should lie flat without touching your neck; if they’re rubbing or causing gaps, the pack size or strap adjustment is wrong. Third, the harness yoke should sit about 5 cm below C7. Finally, your sternum strap should sit roughly level with the bottom of your armpits. REI also notes that finding the right backpack often means trying the pack under load — pressure spots can appear once weight is added.
Common Backpack Fitting Mistakes
THESE FIVE MISTAKES CAUSE most of the discomfort hikers complain about. The most common: wearing the hipbelt too low, letting shoulder straps carry weight the hips should hold, and overtightening the shoulder straps (which creates gaps and rubbing). Below is the at-a-glance rundown:
| Fit Point | Goal |
|---|---|
| Hipbelt | Centered on iliac crest; carries ~80% of load |
| Shoulder straps | Wrap closely, no gaps, no neck contact |
| Load lifters | Pulled to ~45-degree angle toward back |
| Sternum strap | Level with lower armpits; allows free breathing |
| Yoke | Sits ~5 cm below C7 |
Another common miss is skipping the weighted test entirely. Fit the pack, load it, and walk around the house for ten minutes; you’ll discover pressure points and balance issues no static test reveals. And don’t forget: fit systems vary by brand and model, so check the official sizing chart for the specific pack. When you find a pack that fits, the right delivery companion matters too — if you’re training for BJJ trips, you might also want a pick of the best BJJ backpacks for the gym.
FAQs
How much weight should the shoulder straps carry?
Ideally none of the load should rest on the top of your shoulders. The shoulder straps provide stability and keep the pack close to your body — the hipbelt should carry roughly 80% of the pack’s weight, and your lower body absorbs that load.
Can I fit a backpack by height instead of torso length?
No. Height is a poor predictor of torso length because people have different body proportions. Two hikers of the same height can wear very different pack sizes. Always measure your torso length and match it to the manufacturer’s sizing chart.
Why does my backpack hurt my hips?
A hipbelt sitting too high or too low on your hip bones is the usual culprit. The padding should sit directly over the iliac crest. A belt positioned too high can also restrict your diaphragm, so re-check the placement and adjust until the padding hugs the top of your hip bones.
References & Sources
- REI Co-op. “How to Measure and Fit Backpacks.” Covers torso measurement, hipbelt placement, and the proper fit sequence.
- The North Face. “How to Fit and Wear a Backpack for All-Day Comfort.” Details hipbelt straddle, load lifter angle, and weighted fit testing.
- Gregory. “Pack Fit Guide.” Provides C7-to-iliac-crest measurement instructions and weighted testing advice.