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Western Mountaineering AstraLite vs Zpacks Classic Sleeping Bag 20F

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

Western Mountaineering AstraLite is the lighter option — 79 g lighter than the Zpacks Classic Sleeping Bag 20F (15% less weight). If grams matter to you, that is the one to beat.
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Spec Western Mountaineering AstraLite Zpacks Classic Sleeping Bag 20F
Weight 454 g · 0.454 kg · 1.00 lb
size 5'8" (180 cm), the shorter of two sizes (6'4" = 496 g); no Regular/Medium label on page
 533 g · 0.533 kg · 1.18 lb
size Standard-Medium (fits up to 6'0"), 20°F; no size called Regular exists
Brand Western Mountaineering Zpacks
Category Sleep System Sleep System
Western Mountaineering AstraLite
454 g

Ultralight 3-season sleeping bag with 850fp down and 12D shell. Designed for fast-and-light alpine pursuits and long trail journeys.

See it in your base weight → Full details →
Zpacks Classic Sleeping Bag 20F
533 g

Mummy-style sleeping bag rated to 20F (-7C) with 900-fill goose down. DCF outer shell for low weight and packability. Water-resistant treatment included.

See it in your base weight → Full details →

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Western Mountaineering AstraLite vs Zpacks Classic Sleeping Bag 20F: which should you buy?

If saving weight is your priority, the Western Mountaineering AstraLite wins — at 454 g it is 79 g (15%) lighter than the Zpacks Classic Sleeping Bag 20F (533 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 sleep system page, or browse the full gear weight database.

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