Sea to Summit Ultralight Insulated 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 — 248 g lighter than the Sea to Summit Ultralight Insulated (42% less weight). If grams matter to you, that is the one to beat.

Spec	Sea to Summit Ultralight Insulated	Zpacks Classic Sleeping Bag 20F
Weight	595 g · 0.595 kg · 1.31 lb	347 g · 0.347 kg · 0.77 lb
Brand	Sea to Summit	Zpacks
Category	Sleep System	Sleep System

Sea to Summit Ultralight Insulated

595 g

Insulated inflatable pad with R-value 3.7.

Full details →

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.

Check price Full details →

Sea to Summit Ultralight Insulated 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 248 g (42%) lighter than the Sea to Summit Ultralight Insulated (595 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.

More sleep system comparisons

Sea to Summit Ultralight Insulated vs NEMO Equipment Tensor Elite Sleeping Pad Sea to Summit Ultralight Insulated vs Therm-a-Rest NeoAir UberLite Sea to Summit Ultralight Insulated vs NEMO Tensor Elite Ultralight Insulated Sea to Summit Ultralight Insulated vs Zpacks Solo Quilt 20F Sea to Summit Ultralight Insulated vs Nemo Tensor Ultralight Sea to Summit Ultralight Insulated vs Therm-a-Rest NeoAir XLite NXT