What 10,000mAh means on a power bank
How many phone charges you'll really get.
Capacity and output are different
Milliamp-hours describe charge capacity at a specified voltage. Watts describe power delivered at a particular moment. A 45W maximum output does not say how many times a phone can be charged, and 10,000mAh is not a guarantee of delivered capacity at every USB voltage.
Compare watt-hours
Use the battery’s labelled watt-hour rating when comparing energy with a power station. If calculating Wh from mAh, use the voltage that belongs to that capacity figure: Wh = mAh × volts ÷ 1,000. Do not substitute USB output voltage for internal battery voltage.
Expect losses
Conversion and charging consume energy, and the phone may be running while it charges. Battery condition and temperature also affect results. Avoid a universal charge-count claim without testing a named device and a repeatable setup.
Pick for your routine
Check dimensions, available ports and charging profiles. Keep a compatible cable with the bank and try it with your own devices before a trip. For occasional backup, a smaller unit you keep charged may be more useful than a larger one left at home.