Is there really not a way to bring back such a calculator? Not for the "account price", but for calculating the time left to the next account rank...
Your activity is 434
You need 480 activities to be a hero
So 480 - 434 = 46
46 / 14 (2 weeks = 1 period) = 3,2 periods => so you have to pass 4 periods = 2 months.
What about the extra posts in the 2 weeks timeframe, will they be added to the next period?