Gregory Optic 48 vs Zpacks Nero Classic 40L

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

Zpacks Nero Classic 40L is the lighter option — 1,081 g lighter than the Gregory Optic 48 (79% less weight). If grams matter to you, that is the one to beat.

Spec	Gregory Optic 48	Zpacks Nero Classic 40L
Weight	1,370 g · 1.370 kg · 3.02 lb	289 g · 0.289 kg · 0.64 lb
Brand	Gregory	Zpacks
Category	Backpack	Backpack

Gregory Optic 48

1,370 g

Lightweight 48L trail pack with suspended mesh back panel.

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Zpacks Nero Classic 40L

289 g

Frameless ultralight pack in 30L or 40L, built from Dyneema CF fabric. One of the lightest load-carrying packs available for thru-hiking.

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Gregory Optic 48 vs Zpacks Nero Classic 40L: which should you buy?

If saving weight is your priority, the Zpacks Nero Classic 40L wins — at 289 g it is 1,081 g (79%) lighter than the Gregory Optic 48 (1,370 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 backpack page, or browse the full gear weight database.

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