How much mAh can 4700mAh power bank charge?

A 4700mAh power bank can theoretically charge a device that has a battery capacity of up to 4700mAh, assuming 100% efficiency. However, due to energy losses during the charging process (typically around 20-30%), the effective capacity will be less. In practical terms, it may fully charge a device with a battery capacity of about 3000-3700mAh, depending on the device's power requirements and the power bank's output specifications.