Power Banks
Power Bank Size Guide: How Many mAh Do You Actually Need?
Aug
Power Bank Size Guide: How Many mAh Do You Actually Need?
Power banks are sold by capacity (mAh), but the number on the box doesn’t translate directly into charges. Here’s how to pick the right size.
Match capacity to the device
As a rough guide by battery size:
- Phone (~4,000–5,000mAh battery): a 10,000mAh bank gives roughly 1.5–2 full charges.
- A weekend away: 20,000mAh covers a phone for days or tops up a tablet.
- Tablets/laptops: 20,000–26,800mAh with USB-C Power Delivery (higher wattage).
Why you get fewer charges than the math suggests
A 10,000mAh bank does not deliver 10,000mAh to your phone. Energy is lost to voltage conversion and heat, so real-world output is typically around 60–70% of the rating. That’s normal physics, not a defective product — plan for it.
Speed matters as much as size
Capacity is how much; wattage and standards are how fast. Look for USB-C Power Delivery (PD) for phones and especially tablets/laptops. A huge bank with a slow output is frustrating; a smaller PD bank often feels better day to day.
Portability and airline rules
Bigger means heavier. Also note airlines limit lithium batteries in carry-on to 100Wh (about 27,000mAh at 3.7V) without special approval — most consumer banks are under this, but giant ones can be a problem.
Nice extras
A digital % display, multiple ports, wireless charging, and pass-through charging all add convenience.
Bottom line: 10,000mAh is the everyday sweet spot for a phone; step up to 20,000mAh+ with USB-C PD for tablets, laptops, or multi-day trips — and remember you’ll get roughly two-thirds of the labeled capacity in real charges.
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