Osprey Sirrus vs Stratos: which is the right hiking backpack for you?

When it comes to choosing great hiking backpacks for long days on the trail or lightweight overnight adventures, few names carry more weight than Osprey. With decades of design expertise behind every stitch, Osprey consistently delivers packs that hikers trust in some of the world's most demanding conditions — and the Sirrus 36 and Stratos 36 are two of their most popular models. But which one is right for you? In this guide, we break down both packs in detail — comparing features, fit, and performance — so you can make the best decision for your next adventure. Both packs are available now at PAST Outdoors, and both represent some of the finest Osprey backpacks on the market today. 

Two of Osprey's most versatile hiking backpacks, compared side by side

Watch Kris, our retail store manager explain the differences between the Stratos & Sirrus 36L backpacks:

What the Sirrus 36 and Stratos 36 have in common

Before we get into the differences, it's worth highlighting just how much these two Osprey backpacks share in common. Both are built on the same core platform, which means you get the same exceptional quality and thoughtful design regardless of which pack you choose.

Both packs feature Osprey's AirSpeed suspended mesh back panel — a tensioned trampoline-style system that creates an airflow channel between your back and the pack body to maximise ventilation and keep you cooler on the climb. Both also include the Stow-on-the-Go trekking pole attachment, an integrated removable rain cover, dual zippered hipbelt pockets, a hydration reservoir sleeve, a lower sleeping bag compartment, and a side-panel zip for quick access to your layers mid-hike.

Both packs are constructed from bluesign approved 100% recycled nylon with a PFC/PFAS-free DWR finish — meaning you can head into the outdoors knowing your gear has been made with sustainability in mind. If you're still building out the rest of your kit, check out our guide to Osprey backpacks: built for every trail for a broader look at the full range.

Osprey Sirrus 36: great hiking backpacks built for women

The Osprey Sirrus 36 is the women's-specific version of this popular 36-litre platform, and the fit difference is immediately noticeable. Designed with a narrower shoulder harness, a tailored pack bag shape, and a hipbelt that's canted upward to sit more naturally on a woman's hips, the Sirrus 36 delivers a genuinely body-specific carry that makes a real difference over long days on the trail.

The AirSpeed back panel on the Sirrus features an injection-moulded ladder adjustment system providing up to 10cm of torso adjustability, with a taller, wider frame geometry on the latest version to extend the fit range even further. The ErgoPull hipbelt closure system provides leverage when tightening, ensuring a snug, stable fit with optimal load transfer to your hips where it counts most.

Whether you're tackling a full-day ridge walk in the Victorian Alps, a hut-to-hut trek in New Zealand, or a lightweight overnight mission on one of Australia's great wilderness routes, the Sirrus 36 has the capacity, comfort, and organisation to keep you moving confidently from first light to last.

• Women's-specific harness, pack bag shape and hipbelt — designed to fit and perform on a woman's frame

• AirSpeed suspended mesh back panel — maximises ventilation and keeps you cooler on warm Australian days

• Up to 10cm of torso adjustability — fine-tune the fit to your exact body without tools or pack removal

• ErgoPull hipbelt closure — delivers a snug, precise fit with excellent load transfer to the hips

Integrated removable rain cover — stows in its own pocket and deploys instantly when the weather turns.

 

Osprey Stratos 36: great hiking backpacks designed for men

The Osprey Stratos 36 is the men's version of the same platform and one of the most trusted day-and-overnight hiking backpacks in Osprey's lineup. Built with a men's-specific harness geometry — wider shoulder straps, a longer torso range of 45cm to 55cm, and a broader hipbelt — the Stratos 36 is engineered to carry comfortably on a male frame across a wide range of body types.

The suspended AirSpeed mesh back panel on the Stratos creates exceptional airflow between your back and the pack, and the seamless wrap-around hipbelt integrates directly into the mesh backpanel to eliminate hot spots and pressure points. The result is a carry that feels noticeably cooler and more comfortable than a conventional contact-back pack — particularly on longer days in warm conditions.

With 36 litres of capacity, the Stratos 36 sits in the sweet spot for serious day hikers and lightweight overnight adventurers alike. It's big enough to carry everything you need for a full alpine day or a quick one-night mission, while remaining compact enough to move efficiently on the trail.

• Men's-specific harness and hipbelt geometry — engineered for a male frame with a torso range of 45–55cm

• AirSpeed suspended mesh back panel — tensioned trampoline system creates a cooling airflow channel behind your back

• Seamless wrap-around hipbelt — integrates with the mesh backpanel to eliminate hot spots and pressure points

• Lower sleeping bag compartment — keeps your sleep system separate and easily accessible at camp

Stow-on-the-Go trekking pole attachment — carry your poles securely while keeping both hands free on scrambles.

Which Osprey backpack should you choose?

Both packs share the same core design DNA and feature set — the meaningful difference comes down to the gender-specific fit, which Osprey has refined over more than 25 years of development.

Choosing the right fit for your body isn't just about comfort — it directly affects how efficiently your pack transfers load to your hips, how well the back panel ventilates, and how stable the pack feels when you're moving over uneven terrain. A properly fitted Osprey pack feels like an extension of your body on the trail. The wrong fit — regardless of how good the pack is — can lead to shoulder fatigue, hip bruising, and discomfort on longer days out.

Both the Sirrus 36 and Stratos 36 are ideal for day hikes, hut-to-hut treks, and lightweight overnight adventures. For longer expeditions requiring more capacity, explore the rest of our Osprey backpacks range. And if you're heading into multi-day terrain, make sure you're dressed for the conditions — check out our guides to outdoor research hiking jackets, merino base layers, mid layers and raincoats, and navigation essentials for hiking to round out your setup.

Before any adventure, run through our free hiking and camping checklist to make sure nothing gets left behind.

Why buy your Osprey backpack from PAST Outdoors?

At PAST Outdoors, we've built our reputation on one simple principle: we only stock gear we'd genuinely trust on our own adventures. Every Osprey pack we carry has been selected because we believe it represents the best of what's available — and the Sirrus 36 and Stratos 36 are no exception.

Our team are passionate, experienced outdoors people who have spent countless hours on Australian trails — from the Larapinta to the Overland Track — and we bring that real-world perspective to every recommendation we make. We've helped thousands of Australian hikers find their perfect pack, and we know that the right gear genuinely makes the difference between a great adventure and a miserable one.

We stock authentic Osprey backpacks backed by the All Mighty Guarantee, and our customers consistently tell us that our combination of premium product knowledge, genuine enthusiasm, and honest advice sets us apart from the big-box retailers. When you shop at PAST Outdoors, you're not just buying a pack — you're buying confidence for your next adventure.

Browse our full range of great hiking backpacks online at PAST Outdoors today, and take the next step towards your best time outdoors yet.