Just wanted to share a google docs spreadsheet I made for calculating champion points: https://docs.google.com/spreadsheets/d/1IpoH482KKvyK-V4QHmum1rh-BcfCSI4JrqV1PSclg-g/edit#gid=0
Basically you can input your current (or desired) champion level and it'll show you how many points you have to spend in each constellation. You can then put in your points under each constellation and it'll tell you the minimum champion level required for that distribution and highlight any passives it currently gives you.
I found it handy for planning builds as I'm levelling up - hopefully it'll help someone else out too! (Its locked for editing so hit "File", "Make a copy" to save your own version for editing!)