Buying guide
Power Bank Buying Guide (2026)
How to choose a power bank: capacity vs weight, wattage for laptops, airline limits, and ports.
Capacity vs weight: the core tradeoff
Capacity in milliamp-hours (mAh) measures stored energy; weight measures whether you will carry it. A 10,000 mAh bank covers a phone for a couple of days and fits a pocket. A 20,000 mAh bank covers a long weekend and fits a bag. A 24,000 mAh bank covers nearly a week but is a brick. Bigger is not better, it is heavier. Match capacity to your longest stretch away from an outlet.
Wattage: match the bank to the device
Wattage (W) is charging speed. Phones need 18 to 30 W, tablets around 30 W, ultrabooks 45 to 65 W, and larger laptops 90 W or more. A bank must support USB Power Delivery at your device's wattage to charge it properly. This is the most common buying mistake: a huge-capacity bank with 18 W output will not charge a laptop, no matter how many milliamp-hours it holds.
Airline limits
Power banks fly in carry-on baggage only, never checked. Most airlines allow up to 100 Wh without approval; 100 to 160 Wh usually needs permission; above 160 Wh is prohibited. The Wh rating is printed on the bank itself. When a listing only shows mAh, remember that Wh is what the airline cares about.
Ports, passthrough, and displays
Count your devices before counting ports: phone plus earbuds plus watch wants at least two outputs. Passthrough charging lets the bank charge devices while it recharges overnight, handy on nightstands. A display showing wattage or time remaining turns a black box into a tool you can plan around, and it is worth paying a little extra for on banks you use daily.
What to check before you buy
Confirm the wattage covers your hungriest device, the capacity covers your longest trip, and the Wh rating clears your airline's limit. Check that the bank supports the fast-charging standard your phone uses, and buy a cable rated for the wattage if you are pushing 60 W or more. Real-world capacity is always lower than printed capacity, so leave margin.
Questions, answered
How long do power banks last?
Lithium power banks typically hold useful capacity for a few hundred full charge cycles, which is several years of regular travel use. Heat and full discharges accelerate wear; storing at partial charge extends life.
Can I charge a power bank and my phone at the same time?
Only if the bank supports passthrough charging. Without it, the bank prioritizes recharging itself and may not output to devices simultaneously. Check the specs if this matters to your routine.
Why does my 10,000 mAh bank not fully charge my phone twice?
Conversion losses. The printed capacity is measured at the internal cell voltage, and boosting it to charging voltage plus heat loses a meaningful percentage. Expect roughly 60 to 70 percent of the printed figure as usable output.