I was tired of most if not all online mining profit calculators using crappy future difficulty prediction models like static percentage increases, so I made my own. It uses an exponential function made from regression of past statistics to predict the difficulty. I think it will be much more accurate than most other calculators. What do you think?
For now it is just a spreadsheet, link here:
https://docs.google.com/spreadsheets/d/1P_rgP9XnBvuznWdRi7IUKizQHUR0DNxDrl08H90juzc/editCurrently it is set to calculate a SP30 unit delivered in August. If you want to use it you can make a copy of the spreadsheet and edit the values.