It depends on your usage pattern. If you are a salesperson who travels a lot and zips around the cities, 20000 mAh will serve you well. For normal users, 20000 mAh is overkill.u003cbru003eu003cbru003e10000 mAh is the best capacity for most users as you don’t have to charge it too often and can provide a full charge to every smartphone in the market.u003cbru003eu003cbru003e5000 mAh is ideal for users who want an ultra-portable power bank that can be easily carried around.