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Marmot Hydrogen 30°F vs Rab Mythic Ultra (20°F)

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

Rab Mythic Ultra (20°F) is the lighter option — 9 g lighter than the Marmot Hydrogen 30°F (1% less weight). If grams matter to you, that is the one to beat.
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Spec Marmot Hydrogen 30°F Rab Mythic Ultra (20°F)
Weight 709 g · 0.709 kg · 1.56 lb 700 g · 0.700 kg · 1.54 lb
Brand Marmot Rab
Category Sleep System Sleep System
Marmot Hydrogen 30°F
709 g

Ultralight 800-fill down sleeping bag rated to 30°F.

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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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Marmot Hydrogen 30°F vs Rab Mythic Ultra (20°F): which should you buy?

If saving weight is your priority, the Rab Mythic Ultra (20°F) wins — at 700 g it is 9 g (1%) lighter than the Marmot Hydrogen 30°F (709 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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