This plugin will change the behavior of all password fields on IPS4, allowing the administrator to set the minimum length for the passwords. IPS4 default is 3 characters, this plugin will allow you to alter this.
This does work alongside the built-in IPS password strength meter just fine.
It will change the length in all places that uses password, like:
Account Settings -> Password
Existing Users: No changes to their existing passwords. If their password is reset or they change it themselves the new password length requirements will apply.
New Users: Required to use the new password length when they create their account.