This works by working out how many sets of characters you have used from:

- Upper (set of 26)
- Lower (set of 26)
- Numeric (set of 10)
- Symbols (set of 33)

It then works out the number of combinations of passwords that could be made based on the sets that you have used and the password length.

- Weakest < 1000000
- Weak < 1000000000000
- Improving < 1000000000000000000
- Strong < 1000000000000000000000000
- Strongest >= 1000000000000000000000000