Nitecore NB10000 Gen4 review: the lightest full 10,000mAh power bank

The Nitecore NB10000 Gen4 is the bank ultralight hikers and trail runners ask about first, and it is the top pick in our best ultralight power banks guide. This review covers what the spec sheet actually promises, what independent reviewers measured, how it compares with the Gen3 it replaces and its closest rivals, and the one number that matters at the airport.

Who it is for

The Gen4 is built for people who carry a phone, a headlamp, a watch, and maybe a satellite messenger, and who notice every ounce on the climb. Trail runners stuffing a vest pocket, fastpackers on 25-mile days, and thru-hikers who recharge in town every few days get the most from it. Nitecore rates it at 143 g and 116 × 46.8 × 14.5 mm, and The Verge notes it is shorter and narrower than an iPhone 15 Pro, so it fits a vest or hip-belt pocket next to your phone.

It is also a good fit for wet places. IPX7 means it is rated for temporary submersion, so rain, a soaked pack, or a stream crossing should not end your trip. Nitecore's manual adds that it is not designed for underwater use and should be dried before use after a dunk.

Choose something else if:

• You still own USB-A gear. The Gen4 is USB-C only. The Nitecore NB Plus keeps a USB-A port for 12 g more.
• You want the fastest refill on a short town stop. The Nitecore Carbo 10000 Gen2 charges at 30W in both directions and is IPX8, at 170 g.
• Price matters more than grams. The INIU Pocket Rocket P50 weighs 160 g and costs a fraction as much, without a water rating.

Decision snapshot

Best for

Trail runners, fastpackers, and ultralight hikers who want the most energy per gram and a bank that handles rain

Skip if

You need USB-A, 30W fast charging, or the lowest price per mAh

Bottom line

The lightest full 10,000mAh bank in our comparison, with real water protection; you pay a premium for the grams saved.

Buy on Amazon →Nitecore NB10000 Gen4 · Kit Score 8.7/10

Full specifications

Every figure above is Nitecore's published specification unless it is attributed to a reviewer. Nothing in this table is a Kit Authority measurement.

What 39Wh gets you on the trail

Two numbers on the label sound alike and are not. The 10,000mAh figure is measured at the cell's 3.9V. Your phone charges at 5V or higher, and the conversion costs energy, which is why Nitecore lists 6,800 to 7,200mAh as the rated energy at 5V. Watt-hours avoid the confusion: 39Wh in the cell, and The Verge measured 33.58Wh out of it, an 86.1% efficiency.

In practice, The Verge's reviewer fully recharged an iPhone 15 Pro twice with a few watt-hours left. Treeline Review's battery guide uses the same rule of thumb for any 10,000mAh bank: about 1.5 to 2 full smartphone charges, enough for most weekend trips, with thru-hikers recharging in town every three to five days.

Cold cuts into that. CleverHiker measured a 13% efficiency drop in its cold-weather simulation, and Nitecore's operating range bottoms out at -10°C (14°F). On frosty nights, keep the bank in your sleeping bag or an inside pocket, as Treeline Review recommends.

How it compares

Against the NB10000 Gen3. The Gen3 is discontinued on Nitecore's US store. On paper the Gen4 is the same 10,000mAh class with better ingredients: the rated energy at 5V rises from the Gen3's 5,400mAh to 6,800 to 7,200mAh, the input rises from 18W to 22.5W, and water resistance goes from IPX5 to IPX7. Nitecore lists the Gen3 at 5.29 oz and 0.42 inches thick, so the Gen4 is lighter on paper but about 0.15 inches thicker, a change some Nitecore store reviewers mention. The Verge measured 33.33Wh from the Gen3 against 33.58Wh from the Gen4, and saw none of the Gen3's low-battery overheating and shutdowns. CleverHiker adds that the Gen4 brings knock-to-wake, glowing ports, and a touch button.

Against the FLEXTAIL Zero Power 10000. The closest rival. FLEXTAIL lists 145 g, 9.9 mm thin, and 38.7Wh, and CleverHiker rates both banks 4.8 out of 5 for efficiency. CleverHiker's verdict: the Nitecore has more features and better wet-weather protection (IPX7 against FLEXTAIL's IPX4), while the FLEXTAIL is cheaper and slightly better in the cold. See it in our ultralight power bank comparison.

Against budget 10,000mAh banks. The Anker 10K power bank in our travel guide is listed at 8.6 oz, so the Gen4 saves roughly 100 g. The INIU Pocket Rocket P50 closes most of that gap at 160 g and adds a 45W port and a percentage display, but has no water rating. The Verge sums up the trade: the Gen4 costs two to three times a typical 10,000mAh bank and saves 50 grams or more.

What owners and reviewers say

• Editors. CleverHiker names the Gen4 its best power bank overall and rates it 4.8 out of 5, citing weight, efficiency, a fast recharge, and the lanyard cable, and reports it survived an 8-foot drop test. The Verge scores it 8 out of 10, praising class-leading energy density and water resistance. Adventure Alan lists it as the best bank for about two phone charges.
• The complaints are consistent. Price comes up everywhere. The Verge found knock-to-wake worked about 75% of the time and calls the RGB port lights superfluous; both can be switched off. CleverHiker's cons are cold-weather efficiency, no dust rating, and no USB-A port.
• Owners. On Amazon the Gen4 holds 4.1 out of 5 from 38 ratings as of October 3, 2026, a small sample for a new product. On Nitecore's own store it averages 4.5 out of 5 from 119 reviews; the store's review summary highlights the weight, size, fast charging, and lanyard cable, and notes some owners received defective units or saw less capacity than expected.

Airline rules

The Gen4 is printed at 39Wh, well below the 100Wh per-battery limit in the FAA's PackSafe rules, so no airline approval is needed for capacity. Like every power bank, it must travel in carry-on bags; TSA prohibits spare lithium batteries in checked luggage. Some airlines now add their own limits on how many banks you carry and whether you can use them onboard, so check your carrier in our power-bank flight checker and read are power banks allowed on planes for the full rules.

Frequently asked questions

Is the Nitecore NB10000 Gen4 allowed on planes?

Yes, in carry-on bags. It is printed at 39Wh, well below the FAA's 100Wh per-battery limit, so no airline approval is needed for capacity. TSA does not allow power banks in checked luggage, and some airlines add limits on quantity or onboard use, so check your carrier in our power-bank flight checker.

How many phone charges does the NB10000 Gen4 give?

About two for a typical modern phone. The Verge measured 33.58Wh delivered and fully recharged an iPhone 15 Pro twice with a little left over. Larger phone batteries, cold weather, and using the phone while it charges all reduce that.

What is the difference between the NB10000 Gen3 and Gen4?

The Gen4 raises the water rating from IPX5 to IPX7, the input from 18W to 22.5W, and the rated energy at 5V from 5,400mAh to 6,800 to 7,200mAh, and it adds knock-to-wake, lit ports, and a lanyard charging cable. It is listed slightly lighter but is about 0.15 inches thicker. The Gen3 is discontinued on Nitecore's US store.

Is the NB10000 Gen4 waterproof?

It is rated IPX7, which covers rain, splashes, and temporary submersion. Nitecore's manual says it is not designed for underwater use and should be dried thoroughly after an accidental dunk.

Does the NB10000 Gen4 work in cold weather?

Nitecore rates operation from -10 to 35°C (14 to 95°F). CleverHiker measured a 13% efficiency drop in cold conditions, so keep it warm in an inside pocket or your sleeping bag on frosty nights.

Can the NB10000 Gen4 charge a laptop?

It can top up a USB-C laptop slowly. Each port delivers up to 22.5W, and The Verge used it to top up a 14-inch MacBook Pro. For real laptop charging, see our best travel power banks guide, which covers 100W and 140W banks.

Does the NB10000 Gen4 come with a cable?

Yes. The included lanyard is a short USB-C to USB-C charging cable that clips to the bank, so carrying it and charging with it are the same thing. The Verge says it is rated to 60W and weighed it at 6 g.

Where these numbers come from

Specifications are Nitecore's; measured figures belong to the reviewers named. Kit Authority has not published its own measurements of this bank yet.