In order to properly create a useful bitcoin calculator, you need an Excel spreadsheet that has components like this:
Put the price that you know of under the $ column.
Label the months
Click on the D column, under Difficulty + 10%, and place the same value you put beside the Current difficult in previous step, in this case it's (=B6)
Click under the result (1), type =D2+(D2*($B$7/100)), press enter (2), and double click on the small square (3).
Click under Coins/day (1), and type =$B$9*(86400/(D2*((2^32)/($B$2*1000000000)))) (2) and double click on small square (3). Note: 86400 is the seconds in a day.
Click under revenue/day (1), type =E2*$B$9 before pressing enter, and double click on the square (3).
Click under net/day (1), type =F2-($B$3*($B$4/1000)*24) then enter (2), and double click on the small square (3).
Click under Per month (H) column, type =SUMPRODUCT(--(G2-((G2-G3)/30)*ROW(INDIRECT(1&":"&30)))) (2) and double click on the small square (3).
Click empty cell in column G and write Net Annual (1), then beside it on (H) and type =SUM(H2:H13)-B6 and press enter (2)
Here you can download free BitCoin Mining Calculator.