Calculate estimated time of finding string where SHA256(string) starts with n ze

[JohnyCarrot]

Hi have a program that is finding for any string SHA 256 hash that is starting with n zeros. It works like in bitcoin, so i get string for example "FOO", where im finding "nonce" where SHA(FOO+nonce) starts with for example 8 zeros. That nonce is 1231004720 (you can check it BTW)

The program of course works like a charm. I know, that things takes time, but i cant find, if i could calculate estimated time. If i can calculate n=10 in one hour, how much it can take to get 11 leading zeros hash. Somewhere i readed thats its "factor of 16", but IDKif its true and if yes, why ?

Thanks