A pack that fits properly disappears on your back. Weight transfers efficiently, nothing digs or rubs, and you can focus entirely on the trail ahead. A pack that fits poorly becomes a constant distraction. Pressure points worsen by the hour, straps slip, loads shift at the worst moments.
The difference between these experiences isn't luck or expensive equipment. It's understanding how backpack fit works and taking the time to adjust it correctly. This guide covers everything you need to know.
Why proper fit matters
Proper fit influences comfort, stability, and fatigue during long activities.
Comfort over long distances
Minor fit issues compound over distance. What feels acceptable for the first hour becomes painful by hour four and unbearable by the eight. Proper fit eliminates these compounding discomforts before they start. Philip C. confirms this: "Much more comfortable on my back than my old one—nowhere near as sweaty!"
Load distribution
A well-fitted pack distributes weight across your skeletal structure rather than loading muscles that fatigue quickly. This means your hips carry the majority of weight, while your shoulders stabilise rather than bear load.
Preventing injury
Poorly distributed weight strains your back, shoulders, and neck. Over time, this can cause pain and injury. Proper fit keeps weight where your body can handle it without strain.
Performance impact
When your pack moves with you rather than against you, everything becomes easier. Scrambling, jumping across streams, moving quickly on technical terrain all improve when your pack is stable and balanced.
Torso length matters more than height
Two people of identical height can have significantly different torso lengths. One might have long legs and a short torso; another might have the opposite proportions. Pack fit depends on torso length, not overall height.
How to measure
You'll need a flexible tape measure and ideally a friend to help you.
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Find your C7 vertebra. Tilt your head forward and feel for the bony bump at the base of your neck where it meets your shoulders. This is your C7.
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Find your iliac crest. Place your hands on your hips with thumbs pointing backward. The bony ridge your thumbs rest on is your iliac crest.
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Measure the distance. Have someone measure from C7 straight down to an imaginary line drawn between your thumbs across your lower back.
This measurement is your torso length. This number helps determines pack fit.
Size categories
General torso length categories:
- Short: Under 40cm (approximately under 16")
- Medium: 40-48cm (approximately 16-19")
- Long: Over 48cm (approximately over 19")
Most packs are designed to fit medium torsos well, with adjustment systems that extend coverage into short and long ranges. If you're at the extremes, pay particular attention to a pack's adjustability range.
The anatomy of backpack fit
Understanding each component helps you adjust your pack correctly for optimal comfort.
Hip belt: your primary load bearer
The hip belt is the most important fit component. Properly positioned, it transfers 60-80% of the pack's weight directly to your hips and legs, bypassing your shoulders and back entirely.
The hip belt should wrap around your iliac crest, remember that's the top of your hip bones, not your waist. When you tighten it, you should feel the weight lift off your shoulders and settle onto your hips. If the belt sits too high or too low, weight transfer suffers.
Shoulder straps: supporting, not carrying
Contrary to what many assume, shoulder straps aren't meant to carry the load, they're meant to stabilise it. Once the hip belt is doing its job, shoulder straps keep the pack from falling backward and help control load position.
Properly adjusted shoulder straps curve over your shoulders and conform to your chest without gaps. They shouldn't dig into your shoulders (that indicates too much weight on the straps) or have slack (that indicates instability).
Load lifters: the fine-tuning tool
Load lifters are the angled straps that connect the top of your shoulder straps to the pack body. They're the most commonly misunderstood and underused adjustment.
When you tighten load lifters, you pull the top of the pack closer to your body, shifting weight forward and reducing the sensation of being pulled backward. When you loosen them, the pack sits further from your back, which can improve ventilation but reduces stability.
Optimal load lifter angle is typically 25-45 degrees from horizontal. Too flat means the pack is too short for your torso; too steep means it's too long.
Sternum strap: stability and control
The sternum strap connects your shoulder straps across your chest, preventing them from sliding outward. It adds stability without affecting load distribution significantly.
Position the sternum strap about an inch below your collarbone. This is high enough to secure the shoulder straps, low enough not to restrict breathing. Tighten until secure but not constrictive.
Step-by-step fitting process
Follow these steps in order for best results.
Step 1: start with the hip belt
Load your pack with weight representative of what you'll actually carry. This is important because fit changes significantly between empty and loaded packs.
- Loosen all straps and put the pack on.
- Position the hip belt centred on your iliac crest.
- Tighten firmly. You should feel the load transfer immediately.
Step 2: adjust shoulder straps
- Transfer the load to the hip belt
- Tighten the shoulder straps until they conform to your shoulders without gaps. They should wrap over your shoulders and sit flat against your chest.
- Don't over-tighten. If you're pulling weight onto your shoulders, the straps are too tight.
Step 3: set load lifters
- Tighten the load lifters to pull the top of the pack toward your body.
- Watch the angle they create. Aim for 25-45 degrees. The pack should feel stable and centred over your hips.
- If load lifters are at extreme angles (nearly flat or nearly vertical), the pack may not be the right size for your torso.
Step 4: position sternum strap
- Slide the sternum strap to a comfortable height, about an inch below your collarbone.
- Tighten until the shoulder straps feel secure but your breathing isn't restricted.
Step 5: load the pack and test
- Walk around, climb stairs, bend over, twist.
- The pack should move with you, not independently. I
- f it bounces, shifts, or creates pressure points, revisit the adjustments above.
How our 2026 back system improvements help
Our updated pack range incorporates several refinements specifically designed to improve fit across a wider range of body types.
Extended load lifter range
We significantly increased the adjustment range on load lifters across the Ledge 35L and Orion 45L. This effectively changes the back length of the pack without altering its physical size. Users with shorter torsos can cinch the lifters to raise the shoulder attachment; taller users can lower it. This refinement expands the range of torso lengths that achieve optimal fit.
Improved shoulder strap geometry
Updated shoulder strap construction improves how loads transfer across different torso shapes. The straps flex and adapt to your body rather than forcing you to fit a fixed geometry. Whether you're broad-shouldered or narrow-framed, weight spreads more evenly.
Better body type accommodation
Padded mesh hip fins provide support without rigidity, moulding to different hip shapes. The repositionable sternum strap (now with integrated emergency whistle) offers more height options. Together with the load lifter improvements, these refinements mean more people find comfortable fit without compromise. Adam confirms: "The adjustable back system and hip belt makes it very comfortable. Carries weight well." Tony adds: "Having previously used Osprey, Berghaus and Lowe Alpine I can honestly say the Pacific Crest 65L is just as good and in some cases much better... the adjustable back system and hip belt makes it very comfortable, you hardly know you've got it on your back."
For the full technical breakdown, see: The Evolution of Pack Fit
Fit considerations for different body types
Different body proportions require slightly different approaches to achieve optimal fit.
Shorter torso users (under 5'4" / under 163cm)
Focus on packs with high adjustability. Look for load lifters that cinch significantly and hip belts that tighten enough to sit correctly on smaller frames. The extended load lifter range in our 2026 packs specifically addresses fit for shorter torsos.
Taller users (over 6'2" / over 188cm)
Ensure load lifters have enough range to lower the shoulder attachment point. If load lifters sit nearly flat when properly adjusted, the pack may be too short. Our extended adjustment range helps, but very tall users should test fit carefully before committing.
Women-specific fit considerations
Women typically have shorter torsos relative to height, narrower shoulders, and wider hips than men. While we don't currently offer women-specific pack variants, our improved adjustability and pliable hip fins accommodate a wider range of body shapes. Pay particular attention to hip belt positioning and shoulder strap fit.
Broader vs narrower shoulders
The updated shoulder strap geometry in our 2026 range adapts to different shoulder widths better than fixed-angle designs. Broader shoulders benefit from loosening load lifters slightly; narrower shoulders often need them tighter to prevent strap slippage.
Troubleshooting common fit issues
Ensure you have a good fit before you hit the trail.
"The hip belt won't tighten enough"
The belt may be sized too large for your waist. Some packs offer different hip belt sizes. Alternatively, ensure you're positioning the belt on your iliac crest, not your waist. The narrowest point of your torso won't anchor a hip belt effectively.
"Shoulder straps are on full extension"
The pack's back length may be too short for your torso. Try loosening load lifters to their maximum extension. If this doesn't help, consider a pack with a longer back or more adjustment range.
"The pack bounces when you move"
Tighten the hip belt first. Bounce usually indicates weight isn't transferring to your hips. Then check load lifters and shoulder straps. For running or mountain biking, packs like the Idris 25L or Skytrail 14L use body-hugging designs specifically to eliminate bounce.
"You get pressure points on your shoulders"
Weight is on your shoulders instead of your hips. Loosen shoulder straps and tighten the hip belt until you feel load transfer. Adjust load lifters to fine-tune. If pressure persists, the pack may be too long for your torso, causing the hip belt to sit too low.
"The chest strap sits too high/low"
Reposition the sternum strap on its slider. If it can't reach a comfortable height even at its extremes, the shoulder straps may not be fitting correctly. Revisit shoulder strap and load lifter adjustment.
Activity-specific fit adjustments
Different activities benefit from subtle variations in how you adjust your pack.
Trail running and fast movement
Running demands tighter fit overall. The pack should feel like part of your body with zero bounce. Consider packs designed specifically for running, like the Idris 25L, which use flexible foam systems that move with your stride rather than structured panels.
Mountain biking
MTB packs like the Skytrail 14L sit higher on the waist to allow hip movement on the bike. Tighten more than you would for hiking: you need stability during descents when your weight shifts dynamically. As Jules notes: "Sits higher on your waist, rather than on your hips, so enables a wider range of movement."
Mountaineering with heavy loads
Heavy loads benefit from more weight on hips. Ensure the hip belt is firmly anchored and load lifters are set to bring the pack close to your body. For technical sections requiring arm mobility, you can temporarily shift weight to shoulders by loosening the hip belt.
Day hiking
Standard fit principles apply. For shorter days, fit is more forgiving: you can prioritise ventilation (loosening load lifters slightly) over maximum stability.
When to consider a different size
Sometimes adjustment alone isn't enough, and you need a different pack size.
Signs the pack is too big
- Hip belt won't tighten enough even at maximum adjustment
- Shoulder straps have excess slack that can't be removed
- Load lifters sit nearly vertical even when tightened
- Pack extends significantly above your head or below your hips
Signs the pack is too small
- Shoulder straps on full extension still feel tight
- Load lifters sit nearly horizontal
- Hip belt rides up onto your waist rather than staying on your hips
- Sternum strap can't reach a comfortable height
Alternative solutions
Before switching packs, ensure you've explored the full adjustment range. Many fit issues resolve with proper adjustment rather than different sizing. If you're between sizes, consider which direction your load will push you: heavier loads often fit better in slightly larger packs.
Final fitting checklist
Use this checklist every time you adjust your pack:
Hip Belt
- Positioned on iliac crest (hip bones), not waist
- Tightened firmly—majority of weight felt on hips
- Padding centred on hip bones
Shoulder Straps
- Conform to shoulders without gaps
- Not digging in (would indicate too much weight on shoulders)
- Anchor points sit 1-2 inches below top of shoulders
Load Lifters
- Angled at 25-45 degrees
- Pack feels close to body and stable
- No sensation of being pulled backward
Sternum Strap
- Positioned about 1 inch below collarbone
- Secure but not restrictive
- Can breathe deeply without constraint
Movement Test
- Walk, climb stairs, bend, twist
- No bounce or shift
- No pressure points developing
- Weight feels centred over hips
Take the time to get fit right. A few minutes of adjustment translates into hours of comfortable carrying.
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