The 30 to 40 liter range covers almost every kind of hike. At the small end you have room for a long summit day; at the large end you can squeeze in a light overnight. Picking the right size inside that range depends on how much you carry and how often you stay out overnight.
Below we compare seven packs between 35 and 40 liters, from Osprey’s adjustable Kestrel and Kyte to budget packs that include rain covers or a water bladder.
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Quick Picks
- Best overall: Osprey Kestrel LT 35
- Best for women: Osprey Kyte 38 Women’s
- Best budget: Maelstrom 40L Waterproof Backpack
- Lightest budget 40L: Nerlion 40L Hiking Backpack
- Best with bladder: IX INOXTO 40L with 3L Bladder
- Best packable: MIYCOO Ultralight Packable 35L
- Best framed value: Naturehike Rock 40+5L
Comparison Table
| Product | Best for | Capacity | Standout feature | |
|---|---|---|---|---|
| Osprey Kestrel LT 35 | Best overall | 35L | Adjustable torso, raincover | View |
| Osprey Kyte 38 Women’s | Best for women | 38L | AirScape back, adjustable torso | View |
| Maelstrom 40L Waterproof Backpack | Best budget | 40L | 9 pockets, water-resistant fabric | View |
| Nerlion 40L Hiking Backpack | Lightest budget 40L | 40L | About 0.9 kg per brand | View |
| IX INOXTO 40L with 3L Bladder | Best with bladder | 26L/40L | Includes 3L water bladder | View |
| MIYCOO Ultralight Packable 35L | Best packable | 35L | Folds to 4.5 x 3.9 x 7.8 in | View |
| Naturehike Rock 40+5L | Best framed value | 40+5L | Internal frame, hydration-ready | View |
Detailed Reviews
1The Kestrel LT 35 is a classic top-loading rucksack with a men’s fit and an adjustable torso length, so you can dial it to your back instead of hoping a fixed size works.
Osprey gives it a fixed top lid with a zip pocket, stretch side pockets, a front shove-it pocket, trekking pole attachments and a side zip that reaches into the main compartment without unloading from the top. It ships with a raincover. At 35 liters it is the right size for long day hikes and efficient overnights where you carry a light sleep system.
Pros & Cons
What we like
- Adjustable torso length
- Side-zip access to main compartment
- Raincover included
Watch out for
- Men’s fit only in this listing
- 35L is tight for cold-weather overnights
Key Specs
- Capacity: 35 liters
- Fit: men’s, adjustable torso
- Loading: top lid plus side zip
- Raincover: included
- Extras: trekking pole attachment, shove-it pocket
2The Kyte 38 is Osprey’s women’s hiking pack in the 40L class. Its injection-molded AirScape back panel lets you adjust torso length and keeps the load close and stable on technical ground.
It comes with an integrated raincover, trekking pole attachment, a top lid and a fixed hip belt. It is a strong pick for long day hikes, hut-to-hut routes and light overnights for women who want a dialed fit.
Pros & Cons
What we like
- Women’s fit with adjustable torso
- Raincover included
- Stable carry on rough trails
Watch out for
- Fixed hip belt
- Premium pricing
Key Specs
- Capacity: 38 liters
- Fit: women’s, adjustable torso
- Back panel: AirScape
- Raincover: integrated
- Extras: trekking pole attachment
3This version of the Maelstrom swaps to a more water-resistant fabric and spreads storage across nine pockets: the main compartment, two front zip pockets, two hip-belt pockets, two side pockets and two mesh pockets.
The brand lists the pack at about 13.4 x 8.6 x 22 inches, a tall and narrow shape that stays close to your back on narrow trails and in crowded train aisles. Hip-belt pockets are the standout here; snacks, a phone and a map stay reachable without stopping. Like the standard Maelstrom it has no real frame, so treat it as a big daypack rather than an overnight hauler.
Pros & Cons
What we like
- Two hip-belt pockets for snacks and phone
- Water-resistant fabric
- Slim profile for trails and transit
Watch out for
- No frame for heavy loads
- Back panel runs warm in summer
Key Specs
- Capacity: 40 liters
- Size: about 13.4 x 8.6 x 22 in (brand listing)
- Pockets: 9 including 2 hip-belt pockets
- Fabric: water-resistant nylon
- Frame: none
4The Nerlion 40L is a simple, light hiking and travel pack. Nerlion lists the bag at 0.9 kg, and the thick nylon is treated to resist water and abrasion.
One main compartment, several zip front pockets and two side pockets keep it easy to pack. It is a good all-rounder for students, casual hikers and travelers who want one bag for many uses without spending much.
Pros & Cons
What we like
- Light for a 40L pack
- Water-resistant nylon
- Simple, easy layout
Watch out for
- No frame
- Basic hip strap
Key Specs
- Capacity: 40 liters
- Weight: 0.9 kg (brand listing)
- Fabric: water-resistant nylon
- Pockets: main, front zips, 2 side
5IX INOXTO bundles a 3-liter water bladder and a rain cover with its hiking pack, which is unusual at this price. It is offered in 26L and 40L sizes; choose the 40L.
The fabric is high-density water-resistant polyester, and stress points and straps are reinforced. Hands-free hydration is the selling point: you drink more often when you do not have to stop and dig out a bottle.
Pros & Cons
What we like
- 3L bladder included
- Rain cover included
- Reinforced stress points
Watch out for
- Bladder quality is basic
- No frame
Key Specs
- Capacity: 40 liters (also 26L)
- Hydration: 3L bladder included
- Fabric: water-resistant polyester
- Rain cover: included
6MIYCOO’s packable daypack folds down to about 4.5 x 3.9 x 7.8 inches and, according to the brand, weighs about half as much as a phone. Unfolded, it is 12.5 x 8.5 x 20.9 inches.
The fabric has an IPX4 splash rating, so light rain is fine but a downpour is not. It is the lightest way to carry 35 liters, but there is no padding, so keep loads small.
Pros & Cons
What we like
- Folds very small
- IPX4 splash resistance
- Extremely light
Watch out for
- No padding or frame
- Not for heavy gear
Key Specs
- Capacity: 35 liters
- Folded: 4.5 x 3.9 x 7.8 in
- Unfolded: 12.5 x 8.5 x 20.9 in
- Water resistance: IPX4 (brand)
7Naturehike’s Rock pack combines a 40-liter body with a 5-liter extension, an internal frame, a rain cover and a hydration port. The brand lists it at 22 x 10.2 x 7.1 inches.
Ergonomic shoulder straps and a padded back panel make it a real trekking pack rather than a stretched daypack. Naturehike is a well-known camping brand, and this pack sits between budget no-names and premium Osprey models.
Pros & Cons
What we like
- Internal frame
- 40L plus 5L extension
- Rain cover and hydration port
Watch out for
- Fit range not as adjustable as premium packs
- Fewer reviews than Osprey
Key Specs
- Capacity: 40 + 5 liters
- Size: 22 x 10.2 x 7.1 in (brand listing)
- Frame: internal
- Rain cover: included
- Hydration: compatible
How We Chose
We compared published specs, materials, fit ranges and features for more than 40 backpacks in the 30 to 50 liter range, then read verified owner feedback to spot durability and comfort problems that spec sheets miss. We did not receive free products, and we do not claim hands-on testing. TOR Scores combine published specs, verified owner feedback and overall value.
What to Look for in a 40L Hiking Backpack
Forty liters is the sweet spot between a daypack and a full backpacking pack. It holds the Ten Essentials, layers for changing weather, lunch, three liters of water and still has room left for a light sleeping bag on an overnight. Here is what separates a good hiking pack from a big school bag.
- Frame or no frame. Frameless packs (Maelstrom, Nerlion) are light and cheap but feel heavy above about 20 pounds. Internal frames (Osprey, Naturehike, N NEVO) move weight onto your hips and stay comfortable to 30 pounds or more.
- Hip belt. A padded hip belt carries most of the load. A thin webbing strap only keeps the pack from swinging.
- Back ventilation. Mesh or channeled back panels reduce the sweaty patch on hot climbs.
- Rain protection. Most packs are water resistant, not waterproof. A rain cover or a liner bag keeps your sleeping bag and spare clothes dry.
- Hydration. A bladder sleeve and hose port let you drink without stopping, which helps you drink enough.
- Access. Side zips, front shove-it pockets and hip-belt pockets save you from unpacking the whole bag for one item.
For long day hikes, a frameless pack is fine. If you plan to carry a tent, stove and sleeping bag, choose a framed pack with a padded hip belt.
How to Fit a 40L Backpack
Fit matters more than brand. A 40-liter pack with the wrong torso length will hurt even if it is made from the best fabric. Measure your torso from the bony bump at the base of your neck (the C7 vertebra) down to the top of your hip bones. That number, usually between 15 and 21 inches, tells you which size or adjustment range to choose.
Load the pack with about 15 pounds before you adjust it. Then follow this order:
- Hip belt first. Center the padding on your hip bones and tighten until it carries most of the weight.
- Shoulder straps second. Pull them snug so they wrap your shoulders without lifting the hip belt.
- Load lifters third. On framed packs, angle them about 45 degrees to pull the top of the pack toward you.
- Sternum strap last. Clip it about an inch below your collarbones, just tight enough to stop the straps from sliding outward.
If the shoulder straps leave a gap above your shoulders or the hip belt sits on your waist instead of your hips, the torso length is wrong. Packs with adjustable back panels, like the Osprey Kestrel and Kyte, solve that without exchanges.
30L or 40L: Which Should You Choose?
Choose closer to 30 liters if you mostly do day hikes, carry little water or hike in warm weather. You will have a lighter, slimmer pack that is less tempting to overfill. Choose 35 to 40 liters if you hike in changing mountain weather, carry gear for kids or a partner, or want the option of a summer overnight. The extra 10 liters mostly add flexibility, and compression straps make a part-full 40L pack carry like a 30L one.
Related guides: best 40L backpack for hiking, best 35 40L hiking backpack, best 40L backpack hiking, best 40L backpack for backpacking. Browse every pick in our backpacks category.
Sources and further reading: National Park Service: the Ten Essentials, Leave No Trace: the 7 Principles and National Park Service: camping basics. Product specs come from brand listings on Amazon; always check your airline’s current carry-on size rules before you fly.
Frequently Asked Questions
Is a 40L backpack big enough for an overnight trip?
Yes, for a summer overnight with compact gear. A light tent, a compressible sleeping bag, a small stove and one or two days of food fit in 40 liters. Cold-weather trips with bulky layers usually need 50 liters or a pack with an extension collar.
Do I need a frame in a 40L backpack?
If you will carry more than about 20 pounds, yes. An internal frame and padded hip belt move weight onto your hips. For lighter day hikes and travel, a frameless pack is fine.
How do I know what size backpack I need?
Measure your torso from the C7 vertebra at the base of your neck to the top of your hip bones. Match that number to the pack’s size chart or adjustable range.
Are 40L backpacks waterproof?
Most are water resistant rather than waterproof. Seams and zippers let water in during heavy rain. Use a rain cover or a liner bag for anything that must stay dry.
How much should a 40L pack weigh empty?
Frameless 40L packs often weigh around 1 to 2 pounds, while framed hiking and travel packs usually weigh 2.5 to 4 pounds. Wheeled backpacks are heavier, often 4 to 6.5 pounds.
Final Verdict
The Osprey Kestrel LT 35 is our top 30-40L hiking backpack, with an adjustable torso and side-zip access. Women should look first at the Osprey Kyte 38, and budget hikers get a lot for little with the Maelstrom 40L Waterproof.
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