Milliamp hour (mAh) represents a batteries capacity. The higher the number, the more power it can deliver to your device before it also runs out of juice.
Our power banks range from 3350 mAh to 10000 mAh. For context, a Garmin Edge 1030 has a battery capacity of 1900 mAh and most of the latest smartphones have a battery with around 3000 mAh.
You can calculate the approximate number of charges by dividing the power bank's capacity against your device's stated capacity. The outcome is the total number of charges.