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Rab Mythic Ultra (20°F) vs Zpacks Classic Sleeping Bag 20F

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

Zpacks Classic Sleeping Bag 20F is the lighter option — 353 g lighter than the Rab Mythic Ultra (20°F) (50% less weight). If grams matter to you, that is the one to beat.
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Spec Rab Mythic Ultra (20°F) Zpacks Classic Sleeping Bag 20F
Weight 700 g · 0.700 kg · 1.54 lb 347 g · 0.347 kg · 0.77 lb
Brand Rab Zpacks
Category Sleep System Sleep System
Rab Mythic Ultra (20°F)
700 g

Winter-capable sleeping bag at 24.7 oz (700g) with 900-fill hydrophobic down, ideal for 3-season to winter transition camping.

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Zpacks Classic Sleeping Bag 20F
347 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.

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Rab Mythic Ultra (20°F) vs Zpacks Classic Sleeping Bag 20F: which should you buy?

If saving weight is your priority, the Zpacks Classic Sleeping Bag 20F wins — at 347 g it is 353 g (50%) lighter than the Rab Mythic Ultra (20°F) (700 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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