How long a 20,000mAh power bank lasts depends on the battery capacity of the device being charged and the frequency of charging. In general, a 20000mAh power bank can provide 4-6 charges for an average smartphone. This would imply a duration of 4-6 days if you charge your phone daily using the power bank.

This depends on your actual need. Generally speaking, a 20,000mAh power bank is generally considered sufficient for most people's everyday charging needs. However, if you have power-hungry devices or plan to charge multiple gadgets simultaneously, preparing a higher-capacity power bank like the 24000mAh Anker 737 Power Bank (PowerCore 24K) or wired chargers for Samsung or other phones might be more suitable.

Whether a 20,000mAh power bank is better than a 10,000mAh one depends on individual needs and preferences. A 20000mAh power bank can store more energy but are also heavier and bulkier than a 10000mAh power bank. So, if you prioritize portability, a 10000mAh power bank is ideal. But if you prioritize capacity, a 20000mAh power bank is the better choice.

This depends on the battery capacity of your phone. For example, the iPhone 14 has a battery capacity of 3279mAh, then you can calculate it this way: 20000 mAH/3279 mAh ≈ 6.1 times, which means that the 20000mAh power bank can charge your iPhone 14 about 6.1 times theoretically. Note that the actual performance may vary by factors like energy loss, etc.