Charging Calculation

Do you know how many times a power bank can charges phone / tablet? Let see formula below:

Calculation of the conversion rate power bank:
Formula: power bank capacity X 0.8 (about 20% loss) / mobile phone battery capacity = charging times (approximately)

EXAMPLE: Power Bank capacity 11200mah, Mobile phone battery capacity 3100mAh
Formula: 11200mAh X 0.8 / 3100mAh = around 2.89 times

PINENG Power Bank real capacity is about 82.4%. It becasue of power bank battery has performance loss when charging, estimated battery loss is about 20%.