Power banks are the rare gadget where the most common buying mistake is obvious once it’s pointed out: people pick the biggest mAh number they can afford and end up carrying a heavy brick they never fully use. Spend time in r/EDC or r/gadgets and the seasoned advice is the opposite — figure out the job first, then buy the smallest bank that does it, because the one you actually keep in your bag beats the one too bulky to bring. We marked this “default that stuck” because the category has a clear, durable front-runner on the merits, but the real decision is capacity and ports, not brand.
Two facts worth front-loading, because they cut through the marketing. First, the mAh number on the label is the cell’s rating, not what reaches your phone — conversion losses mean a 10,000mAh bank delivers meaningfully less than 10,000mAh to your device, so the honest expectation is “roughly two phone charges,” not the math on the box. Second, for anything bigger than a phone, the spec that matters is USB-C Power Delivery wattage, not capacity — a huge battery with a weak port still charges your laptop slowly.
The short version
| Capacity class | Best at | Rough size | The complaint that keeps coming up |
|---|---|---|---|
| 5,000–10,000mAh slim | Daily pocket top-up; ~1–2 phone charges; barely adds weight | Pocketable | Won’t get you through a multi-day trip; modest output |
| 20,000mAh travel | All-day / multi-device travel; charges phone several times | Bag-sized, heavier | Bulky and airline-limit-adjacent; overkill for daily carry |
| Laptop-class (USB-C PD, 65W+) | Charging laptops and phones on the move | Larger, heavier | Expensive; heavy; you must check the wattage, not just mAh |
| Rugged / solar | Outdoors, camping, unreliable power | Bulky, heavy | Solar charging is slow and oversold; heavy for everyday use |
The slim 5,000–10,000mAh bank: what most people should actually buy
For the largest group of buyers — people who want a daytime safety net for their phone — a slim 5,000 to 10,000mAh bank is the right answer, and it’s the one people most often skip past on their way to something heavier. It tops a phone up once or twice, slips in a pocket or small bag without you noticing, and you’ll actually carry it, which is the whole point. The r/EDC consensus leans hard toward “smaller than you think” for daily carry, and they’re right: a bank you leave at home because it’s a brick has zero capacity when you need it.
Who it’s not for: travelers who’ll be away from outlets for a full day or charging multiple devices — you’ll run a slim bank dry and resent it. It’s also not for tablet or laptop users. Buy this if your honest need is “don’t let my phone die during the day”; size up only if you can name a trip or device that demands it.
The 20,000mAh travel bank: the all-day, multi-device workhorse
Step up to around 20,000mAh and the use case is clear: a full day out, a flight, or keeping a phone plus earbuds plus a friend’s dying phone alive. It’ll recharge a phone several times and usually has two ports so you can charge two things at once. For travel, the recommendation threads converge here as the do-everything size. One practical note people forget: most airlines cap the battery capacity you can carry on, and 20,000mAh is comfortably under the common limit while larger banks can run into trouble — so this size is also the sweet spot for flying.
Who it’s not for: daily commuters, for whom it’s needless bulk and weight you’ll stop carrying. And it’s not a laptop charger unless it specifically has a high-wattage USB-C PD port — capacity alone won’t charge a laptop fast. Buy this for travel and heavy multi-device days; don’t make it your everyday pocket bank.
Laptop-class USB-C PD banks: for working away from an outlet
If you need to charge a laptop on the move, capacity is secondary — you need a bank with a USB-C Power Delivery port rated high enough (commonly 65W or more) to actually feed the laptop, ideally enough to run it, not just trickle. These are bigger, heavier and pricier, and the spec that matters is the wattage printed in the fine print, not the headline mAh. People who work from trains and cafés point to this class and stress checking the output wattage above all.
Who it’s not for: anyone who only charges phones — you’d be hauling weight and paying for output you’ll never use. It’s a specialist tool for laptop users. Buy it if you genuinely work off a battery; check the PD wattage against your laptop’s charger before you trust it.
Rugged and solar banks: outdoors only, with realistic expectations
For camping, hiking and unreliable-power situations, rugged banks add water resistance, drop protection and sometimes a built-in solar panel. They’re genuinely useful in the field. But the community is blunt about one thing, and it’s the most oversold feature in the category: the built-in solar panels are slow — useful as a trickle top-up in an emergency, not a real way to recharge a big bank in any reasonable time. Treat solar as a backup, not a charging strategy.
Who it’s not for: everyday users, who are paying a weight-and-bulk penalty for ruggedness they don’t need, and anyone expecting solar to meaningfully recharge the bank — manage that expectation or you’ll be disappointed. Buy rugged for actual outdoor use; charge it from the wall before you leave and treat the panel as insurance.
Why Anker keeps winning — and where it’s just preference
The reason Anker is the name that recurs isn’t a single killer feature; it’s the boring stuff that decides whether you trust a power bank for years: honestly-rated capacity, reliable charging, decent support and broad availability. That’s exactly what “a default that stuck” means — not the flashiest, but the one people buy, keep, and recommend without drama. The honest caveat is that several other brands make perfectly good banks, and once you’re matching the right capacity and ports, the brand premium matters less than the community’s habit suggests. Anker is a safe default, not the only correct answer.
So what should you actually use?
- Just want your phone to survive the day? A slim 5,000–10,000mAh bank — and you’ll actually carry it.
- Traveling or charging several devices all day? A 20,000mAh bank — also the sweet spot for flying.
- Charging a laptop on the move? A USB-C PD bank rated 65W+ — check the wattage, not the mAh.
- Heading outdoors or off-grid? A rugged bank — and don’t count on the solar panel.
- Overwhelmed by the numbers? Buy a reputable, honestly-rated bank in the smallest size that does your job; bigger is not better if it stays home.
There’s no single best power bank because the right one is a function of your actual day, not a spec ranking. The durable agreement in the threads is the part the marketing fights: match the capacity to the job, respect the conversion losses and PD wattage, and buy the smallest thing that works — because the bank in your bag is worth infinitely more than the bigger one on your shelf.
Consensus as of mid-2024. Capacities and airline limits are summarized from manufacturer and carrier guidance and can change; verify current rules before flying. The Test Desk takes no affiliate commission and accepts no sponsorship — this is a synthesis of public discussion and published specs, weighted toward long-term-use sentiment, with the usual caveat that gadget subreddits aren’t a representative sample of all buyers.