When purchasing a power bank, you need to consider 3 specs as follows:
Capacity - This is how much juice the power bank holds, usually measured in milliamp-hours (mAh).
Input - This is the amount of power required to recharge the power bank itself.
Output - This is the amount of power the charger can give to other devices.
Port - This is the type of socket or connector. A lot of power banks are now recharged via a USB-C port, but they can often give power out via USB-A (the traditional style USB plug) too.
Size Vs Power
As with everything in life, your power bank is a compromise. You’ll have to balance how much power you want with how big of a brick you want to carry around with you. A pocket-size charger isn’t going to keep you going through a week in the wilderness, but a big slab of plastic isn’t going to look great dangling out of your purse in the bar.
Pocket Chargers (3000-9000 mAh) will get you one, or maybe two, full charges for your phone so they’re great for a night away. They also come in hundreds of colors, shapes, and sizes, so you can style it out or keep it hidden. Generally, at this size, you’ll also be able to give your tablet a slow charge but it might not reach 100%—laptops and anything bigger are out of the question.
Medium Chargers (9000-15000 mAh) will get you at least two or three charges for your phone or one for a tablet. They’re usually too big and heavy for a pocket so you’ll have to carry them in a bag if you’re on the go. Depending on the power bank’s output, you’ll potentially be able to start charging laptops in this range.
Big Chargers (15000 mAh+) are basically unlimited in how many charges they can give and what devices they can power. These power banks can keep your phone charged for a week or more and can power anything from laptops to anything!
