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As some of you already know, I've been publishing about Osprey backpacks for the last 2.5 years now (find full post list at the bottom).
I thought a post around Osprey Stratos vs Kestrel would be helpful for most of you as they're quite a bit similar.
In short, Stratos 36 and Stratos 50 offer 1 more additional zippered pocket at the front, and a bit more ventilation than Kestrel 38 and Kestrel 48.
But their weight distribution and external gear attachment capabilities are a bit lower, and with Stratos 36, you can't install your water bottle inside side mesh pockets without taking off the pack.
- #A sidenote here: REI's backpack capacity chart is GOLD. Highly recommend you to check it out before you read any further.
Osprey advertises both lines as backpacking backpacks (source at osprey.com for Stratos | Sirrus and Kestrel | Kyte).
Because they have tons of similarities.
- There's almost no difference in the weight department between Stratos 36 & Kestrel 38 and the Stratos 50 & Kestrel 48.
- All 4 of them offer 3 accesses to the main compartment (top, bottom and side).
- They offer very similar (could have even said "identical") suspension capabilities, ventilation performances, pocket configurations and design intentions.
- All come with an integrated raincover.
- They both offer 2 sizes (S/M and M/L).
- In my Best Osprey Hiking Backpacks post, I rated both of them a 8/10 in comfort and features departments.
And the list goes on and on...
If you're looking to get a backpack suitable for backpacking and/or hiking, I'm pretty sure you can't go wrong with either of them.
- Bold are my top picks for each group (based on trip length).
- If you tend to pack more or less than the average person, then shift the trip length values accordingly.
- If you're planning to get either one of them, I'd also highly recommend you to check out Osprey's own PackFinder tool as well.
To see the full table and my top picks, visit my post Best Osprey Hiking Backpacks.
Rotate your phone sideways for a better table display.
Features & Organization
Weight (M Size)
Trip Length: 7+ nights [>90 L]
Xenith 105 (Men's)
Trip Length: 5-7 nights [75 - 90 L]
Xenith 88 (Men's)
Xena 85 (Women's)
Aether AG 85 (Men's)
Ariel AG 75 (Women's)
Trip Length: 2-5 nights [55 - 75 L]
Sweet spot. Versatile picks.
Atmos AG 65 (Men's)
Aura AG 65 (Women's)
Xenith 75 (Men's)
Xena 70 (Women's)
Volt 75 (Men's)
Viva 65 (Women's)
Aether PRO 70 (Men's)
Ariel PRO 65 (Women's)
Aether AG 70 (Men's)
Ariel AG 65 (Women's)
Aether AG 60 (Men's)
Ariel AG 55 (Women's)
Volt 60 (Men's)
Rook 65 (Men's)
Renn 65 (Women's)
Levity 60 (Men's)
Lumina 60 (Women's)
Exos 58 (Men's)
Eja 58 (Women's)
Trip Length: 1-3 nights [45 - 55 L]
Atmos AG 50 (Men's)
Aura AG 50 (Women's)
Kestrel 48 (Men's)
Kyte 46 (Women's)
Stratos 50 (Men's)
Sirrus 50 (Women's)
Levity 45 (Men's)
Lumina 45 (Women's)
Exos 48 (Men's)
Eja 48 (Women's)
Rook 50 (Men's)
Renn 50 (Women's)
Viva 50 (Women's)
Trip Length: 0-1 nights [<45 L]
Kestrel 38 (Men's)
Kyte 36 (Women's)
Stratos 36 (Men's)
Sirrus 36 (Women's)
Talon 44 (Men's)
Tempest 40 (Women's)
Talon 33 (Men's)
Tempest 30 (Women's)
Exos 38 (Men's)
Eja 38 (Women's)
If you're interested in getting a travel backpack, check out my Osprey's top travel backpacks post.
Having said that... They do have some minor differences.
- Stratos 36 & 50 come with an additional front zippered pocket (7 pockets at total + main & sleeping bag compartments) which allows making more of your frequently used items readily available.
- Don't confuse this pocket with the front pouch! Front pouch isn't zippered and it is also offered by the Kestrel line - unlike the front zippered pocket.
- They also offer a little bit more ventilation than the Kestrel's. You can say they're more for warm weather use.
- Kestrel 38 & 48 lack this pocket, which means that the total number of exterior pockets add up to 6 (+ main & sleeping bag compartments). 1 pocket less than Stratos.
- But they offer superior external gear attachment capability (bungee tie-offs, loops and daisy chains). They're perfect for attaching ice tools, snow shoes, etc. This too makes the Kestrel a more suitable option for winter adventures compared to Stratos.
- They also perform a little bit better in terms of distributing its weight throughout your entire body to ensure a more effective carrying.
In short, my recommendations would be as follows:
- Kestrel 38: The most suitable option for day hiking unless you're a heavy sweater.
- Kestrel 48: If you're like most people and incredible external gear attachment capability isn't crucial for you... or, in other words, if you'll be backpacking, say, %80+ of the time with your pack... then I'd probably recommend the Stratos 50 over the Kestrel 48.
- Stratos 36: For heavy sweaters, this can be a superior alternative to Kestrel 38, but read on.
- Stratos 50: The most suitable option for multi-day hiking & camping trips.
Most of you are probably also wondering about of their differences in the suspension.
Let's take a look at it first and then compare the Stratos 36 to Kestrel 38, and the Stratos 50 to Kestrel 48.
AirScape vs AirSpeed
The way I see it, there's a little bit of a confusion going on about these suspension systems.
Some of you might have read that the AirScape (belongs to Kestrel) and AirSpeed (belongs to Stratos) are focused on effective weight distribution and ventilation departments respectively.
Now this is true. Because even Osprey themselves explain something similar in their suspension technology page (source at osprey.com).
But... these differences aren't huge by any means. Might not even be that noticeable for most of you.
Stratos 36 vs Kestrel 38
Unless you're a heavy sweater, I'd recommend you the Kestrel 38.
- Stratos 36 doesn't allow horizontal access to the mesh water bottle holders at each side (meaning that you'll have to take off your pack when loading & unloading it). And it comes with less external gear attachment.
- However, it's a little bit more ventilated than the Kestrel 38, and also offers an additional zippered pocket at the front.
I value the features of Kestrel 38 more than I do those of Stratos 36. And I also think that most of us average recreational hikers would be the same.
Compared to Kestrel 38, Stratos 36 comes with less external gear attachment options.
Now I don't really have much problems with this unless I'm going on a winter adventure so I need things like snowshoes, ice tools, trekking poles, etc.
But one thing I don't like about Stratos 36 is that unlike all the other models in this review, it doesn't offer horizontal access to the mesh water bottle holders at each side.
I always wish having this feature when hiking - as it allows loading and unloading on the go, without having to take off your pack.
Stratos 36 does have its advantage, though. It's a bit more ventilated due to it's different suspension and harness system (it does inevitably sacrifice a little bit weight distribution performance in return, though).
It also offers an additional front zippered pocket, which is lacking in Kestrel 38.
However, this pocket is prone to getting squeezed if/when the pack is overloaded and hence bloated outwards to the front.
It comes down to your preferences. Comfort & ventilation wise, both packs are solid and I rated them 8/10 in my Best Osprey Backpacking Backpacks post.
Both Stratos 36 and Kestrel 38 would be suitable for day hiking and occasional overnight camping. It's difficult to go wrong with either one of them.
If you think that you wouldn't be camping (or even if you do so it'd be with ultralight gear) and just would be day hiking with your backpack, then I'd recommend you to check out Talon 33 [read my review].
It's a more streamlined and less feature rich alternative to these packs, as I explained more in my Stratos vs Talon post.
Stratos 50 vs Kestrel 48
This is easier to decide.
Unless incredible external gear attachment capability is crucial for you (which I'd doubt), I'd recommend you the Stratos 50 over Kestrel 48.
The front zippered pocket will come more useful as it's less likely to get squeezed due to the bloated main compartment that pushes the equipment outwards to the front.
Unlike Stratos 36, it is possible to access the water bottle holders on the go with the Stratos 50.
You're also more likely to wish top notch ventilation when you're hauling 48-50 liters worth of equipment when it's warm than you do so with 36-38 liters of it.
Here's a good video review of the Stratos 50:
Mark Brozak says
Thanks, great reviews and comparisons! As I am looking at possibly doing the Camino de Santiago, I was comparing both the Kestrel 48 and Stratos 50 online to get as much info as possible before going to the local outdoor shop. This was a good breakdown along with the recommended YouTube video (which I had also watched). Appreciate your insight and recommendation!
Hi, I have read through all your comparison reviews on the Atmos, Ariel, Stratos/Sirrus…. and decided on the Sirrus 50L. So I went online and searched to get it, but no where to be found… I found on a youtube video that the Stratos/Sirrus 50L has been discountine?!?! I am not sure if it is true, do you guys know?
If so, do you guys think the Aura 50 would be the way to go (as I prefer ventilation and comfort！ Thanks so much!
Stratos 50 and 36 are still sold, I bought one today.
Thank you so much for taking the time to do these Osprey reviews! I have gotten to the point where I won’t buy one until I have come to your website and checked out what you have to say about them. Being a bit of an Osprey fanboy myself, at one time I had two 22’s, a Statos 24, a Stratos 34 and an Aether Plus 70. However, I ended up selling one of the 22’s and the 34 and got the Stratos 50 based on what I read here. I usually day hike with the occassional weekend trip, so I think that is enough for my needs. I like the outer zippered pocket on the Stratos line as I don’t pack so much that it renders that pocket unusable. I also find that the Stratos holds my hiking poles better than the Talon, since I can cinch them down at the top to keep them from wiggling around when I walk. Overall, I agree with your assessments and sincerely appreciate being able to rely on them when thinking about ticking off my girlfriend by buying another pack…….Take care, and happy hiking!