Convert

The Convert feature allows you to exchange all of your current power points for extra Battle Stars, or to increase your score. You can access it from the Boot Camp. It can only be done once per day (UTC time / daily reset)

See Country HQ for the other kind of daily Convert.

Amount
The reward you get for score is based on the score you currently have, and what your all-time power points was at the last time you converted in the current Boot Camp. For Battle Stars, the reward is based on what your all-time power points was at the last time you converted in the current Boot Camp, what the total next upgrade cost of all your HQ upgrades is, (only upgrades that you have bought at least one level will count.) and how many Privatization points you have.