Zend certified PHP/Magento developer

How know how many passwords i need in a wordlist?

I would like to know how many passwords I need to create a wordlist, the permutations before create the wordlist. For example if I want to create a wordlist from 1 to 9 there are 9 passwords, very easy, but if i need create a wordlist with all the permutations about aaaaa to zzzzz.

Are there any tool or script?