The NU25 UL is the ultralight pick. At 1.59 oz including battery, it's the lightest serious headlamp here by a significant margin, and 400 lumens with USB-C rechargeable is more than acceptable for typical backpacking use. The trade-offs are predictable for an ultralight: lower IP rating, smaller battery, and a thinner strap. For thru-hikers and weight-counting backpackers, this is the canonical headlamp pick — and at $45, it leaves room in the budget.
Strengths
- +Just 1.59 oz (45 g) — lightest headlamp in this round-up
- +400 lumens max output is competitive with the Black Diamond Spot 400-R despite the weight savings
- +USB-C rechargeable with up to 45 hours of runtime in ultralow mode
- +Spotlight, floodlight, and red light modes
- +Cheapest premium-tier rechargeable headlamp in this lineup
Watch-outs
- −IP66 splash-resistant only — less robust than the Black Diamond Spot 400-R or Fenix HM55R
- −Smaller battery means shorter runtime at high output (2 hr 45 min @ 400 lm)
- −Tighter elastic strap may be uncomfortable for users with larger heads
- −Less premium build quality than the Petzl Actik Core or Fenix HM55R
How it compares
Lightest pick by a wide margin — 1.59 oz vs the Petzl Actik Core's 2.65 oz and the Fenix HM55R's 3.07 oz. Tied with the BioLite HeadLamp 425 on lumen output (400-425 lm) but in a much smaller package. Loses to the Fenix HM55R and Black Diamond Spot 400-R on waterproofing and to the BioLite HeadLamp 425 on comfort.
Who this is for
At a glance: ultralight backpackers and thru-hikers who weigh every gram and need 400 lumens in 1.59 oz.
Why you’d buy the Nitecore NU25 UL
- Just 1.59 oz (45 g) — lightest headlamp in this round-up.
- 400 lumens max output is competitive with the Black Diamond Spot 400-R despite the weight savings.
- USB-C rechargeable with up to 45 hours of runtime in ultralow mode.
Why you’d skip it
- IP66 splash-resistant only — less robust than the Black Diamond Spot 400-R or Fenix HM55R.
- Smaller battery means shorter runtime at high output (2 hr 45 min @ 400 lm).
- Tighter elastic strap may be uncomfortable for users with larger heads.
Rating sources
Our 4.3 score is the average of these published ratings. More about methodology.
