Therm-a-Rest Hyperion 20F/-6C (Regular) vs Western Mountaineering AstraLite

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

Western Mountaineering AstraLite is the lighter option — 71 g lighter than the Therm-a-Rest Hyperion 20F/-6C (Regular) (13% less weight). If grams matter to you, that is the one to beat.

Spec	Therm-a-Rest Hyperion 20F/-6C (Regular)	Western Mountaineering AstraLite
Weight	567 g · 0.567 kg · 1.25 lb	496 g · 0.496 kg · 1.09 lb
Brand	Therm-a-Rest	Western Mountaineering
Category	Sleep System	Sleep System

Therm-a-Rest Hyperion 20F/-6C (Regular)

567 g

Ultralight 20F down mummy bag with 900-fill Nikwax Hydrophobic Down for fast-and-light backpacking.

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Western Mountaineering AstraLite

496 g

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

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Therm-a-Rest Hyperion 20F/-6C (Regular) vs Western Mountaineering AstraLite: which should you buy?

If saving weight is your priority, the Western Mountaineering AstraLite wins — at 496 g it is 71 g (13%) lighter than the Therm-a-Rest Hyperion 20F/-6C (Regular) (567 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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