This is a question we are often asked. The Cloudbank has 20,000mah of stored power and to find out how many times you can recharge your device you need to find out how big the battery on the device you want charged is.
For example the iPhone 7 uses a 2,000mah battery. 20,000/2,000 = 10. So you would get roughly 10 recharges from the Cloudbank