To know what charger would best serve your needs you need to understand your device's battery capacity:
As our mobile device's continue to advance the battery capacities are not keeping up with the enhanced functionality. Below is a chart of the mAh capacity of some of the most common mobile devices. Once you know the capacity (ie. iPhone 5s battery capacity is roughly 1600 mAh) you know you will need a charger with a minimum capacity greater than that of your phone to provide a full charge, if your device remains turned off when charging.
A key concept to understand when evaluating how many times a charger will charge your device before it needs to be recharged is that if your phone is on when charging it is now drawing its power directly from the charger that is also charging the battery. This will increase the time it takes to recharge your device as well as draw a lot more of the chargers capacity than if the phone remains off during charging.
So, if you know you will be using your phone while charging it than opt for a charger with a capacity close to double your devices battery capacity as this will provide a full charge.
|Phone Model (click the model to view device stats)||Capacity (mAh)|