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Osprey Atmos AG 50 vs Outdoor Vitals CS40 Ultra Backpack

Weight and specs compared for 2026 — and which one to choose.

Outdoor Vitals CS40 Ultra Backpack is the lighter option — 1,135 g lighter than the Osprey Atmos AG 50 (60% less weight). If grams matter to you, that is the one to beat.
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Spec Osprey Atmos AG 50 Outdoor Vitals CS40 Ultra Backpack
Weight 1,900 g · 1.900 kg · 4.19 lb 765 g · 0.765 kg · 1.69 lb
Brand Osprey Outdoor Vitals
Category Backpack Backpack
Osprey Atmos AG 50
1,900 g

Versatile 50L Anti-Gravity pack for multi-day adventures.

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Outdoor Vitals CS40 Ultra Backpack
765 g

40L ultralight backpack with carbon fiber frame stays. Weighs 27oz and supports up to 35 lbs with full functionality.

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Osprey Atmos AG 50 vs Outdoor Vitals CS40 Ultra Backpack: which should you buy?

If saving weight is your priority, the Outdoor Vitals CS40 Ultra Backpack wins — at 765 g it is 1,135 g (60%) lighter than the Osprey Atmos AG 50 (1,900 g). That said, the heavier option may justify the extra grams with more capacity, durability or comfort, so weigh the trade-off against how you'll use it.

See where both rank against everything else in this category on the lightest backpack page, or browse the full gear weight database.

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