Ultralight Backpacks: 9 Packs Compared per Liter and Load
How we did this: we took each pack’s weight at size medium with its standard belt or straps from the maker’s own page, checked on 29 Sep 2026, and divided by volume and into its load rating. We note whether each maker’s load figure is a maximum or a comfort rating. We have not field-tested these packs.
Ultralight backpacks for overnight and thru-hiking trips weigh 22.5 to 38.5 oz among the nine most-compared models. Most land close together per liter, 0.56 to 0.64 oz. The outliers are Zpacks’ two packs, the Arc Haul Ultra 60 at 0.38 oz per liter and the Arc Zip Ultra 62 at 0.41, both with a 40 lb maximum. Price runs from $199 for the Durston Kakwa 55 to $420 for Hyperlite’s Dyneema packs.
Ultralight backpacks compared
| Pack (size M) | Weight | Volume | Per liter | Load rating | Load per oz of pack | Price |
|---|---|---|---|---|---|---|
| Zpacks Arc Haul Ultra 60 | 22.5 oz | 60 L (47 L main body) | 0.38 oz | 40 lb max (30–35 comfortable) | 1.78 lb | $399 |
| Zpacks Arc Zip Ultra 62 | 25.3 oz | 62 L (47 L main body) | 0.41 oz | 40 lb max (30–35 comfortable) | 1.58 lb | $449 |
| Gossamer Gear G4-20 42 | 24.8 oz | 42 L (30 L main body) | 0.59 oz | 30 lb max (25 comfortable) | 1.21 lb | $205 |
| Durston Kakwa 55 (UltraGrid) | 30.6 oz | 55 L (+ 15 L external) | 0.56 oz | 45 lb comfortable (no max given) | 1.47 lb | $199 |
| Hyperlite Southwest 55 | 30.8 oz | 55 L (+ 13.4 L external) | 0.56 oz | 40 lb max | 1.30 lb | $420 |
| Hyperlite Windrider 55 | 31.1 oz | 55 L (+ 13.4 L external, mesh pockets) | 0.57 oz | 40 lb max | 1.29 lb | $420 |
| Gossamer Gear Gorilla 50 | 31.9 oz | 50 L (32 L main body) | 0.64 oz | 30 lb max (25 comfortable) | 0.94 lb | $275 |
| Gossamer Gear Mariposa 60 | 34.2 oz | 60 L (36 L main body) | 0.57 oz | 35 lb max (30 comfortable) | 1.02 lb | $315 |
| ULA Circuit | 38.5 oz | 68 L (total) | 0.57 oz | 35 lb max | 0.91 lb | $299.99 |
Sources: each maker’s product page, linked in the table, checked 29 Sep 2026. Per-liter and load-per-ounce figures are our calculation; per liter uses each maker’s headline volume, which some count with pockets and some without.
How to choose between them
- Start with your full load. Add base weight, food and water for your longest carry. Pick a pack whose rating covers it, checking whether the maker gives a comfort or a maximum figure.
- Then volume. Size it to your bulkiest kit. A bear canister needs main-body room, not pocket space, so compare the main-body figures where makers give them.
- Then fabric and price. Hyperlite’s woven Dyneema packs cost $420; Robic nylon and UltraGrid packs cost $199 to $315.
Zpacks Arc Haul Ultra 60: lightest per liter
Zpacks lists 22.5 oz for a medium torso with standard straps and a medium belt, and 60 L: 47 L of main body, 2.5 L in each side pocket and 8 L in the center pocket. Zpacks rates it 30 to 35 lb comfortably and 40 lb maximum, for $399. Vest-style straps add about 3 oz.
The Arc Zip Ultra 62 is its larger sibling: 25.3 oz for 62 L (47 L main body, 10 L center pocket), the same 40 lb maximum, $449, according to Zpacks.
Check price →Durston Kakwa 55: best value
At $199 in UltraGrid, the Kakwa costs less than half as much as the Hyperlite packs, matches their 55 L inside and carries Durston’s 45 lb comfort rating. Full comparison: Kakwa 55 vs Southwest 55.
Check price →Hyperlite Southwest and Windrider 55
The same 55 L Dyneema Woven Composite body, rated to 40 lb, $420. The Southwest has solid-fabric outside pockets for abrasive terrain (30.8 oz); the Windrider has large-hole mesh pockets (31.1 oz). See our Hyperlite Southwest review.
Check price →Gossamer Gear and ULA
Gossamer Gear’s G4-20 (24.8 oz, $205) is the light frameless option; the Gorilla 50 and Mariposa 60 add an aluminum frame and pivoting hipbelt. ULA’s Circuit is the heaviest here at 38.5 oz but the largest at 68 L, for $299.99. See all 8 Gossamer Gear packs.
Head-to-head comparisons
- Gossamer Gear G4-20 42
- Durston Kakwa 55 (UltraGrid)
- Hyperlite Southwest 55
- Gossamer Gear Gorilla 50
- Gossamer Gear Mariposa 60
- ULA Circuit
FAQ
What is the lightest ultralight backpack per liter?
Which ultralight backpack carries the most?
What is the cheapest good ultralight backpack?
Hyperlite Windrider or Southwest?
Why are your weights different from the makers' headlines?
The bottom line
Most ultralight backpacks weigh about 0.56 to 0.64 oz per liter; Zpacks’ Arc Haul Ultra 60 (0.38) and Arc Zip Ultra 62 (0.41) are the exceptions. For value, the Durston Kakwa 55 at $199; for a waterproof-fabric pack, the Hyperlite Southwest or Windrider at $420.
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