Race Time Goal Tracking Spreadsheet or App?

I am looking for a spreadsheet or app to help keep track my goal as I progress thru a 100 Miler. It would have a spot to enter the desired goal, it would use distance covered and time elapsed to calculate progress toward the goal (100 miles n 24 hours).
At a given moment, as the runner slows down, the spreadsheet would show if the goal is attainable before the cutoff. I have created a static sheet with different paces and I know if I exceed 14 minute per mile, I will not meet the 100 miles in 24 hours. But you know that I can start at 10 minute pace, but I will start to slide and I want my crew (wife) to be able to just plug in the numbers and predict the future. Anyone know where I can find a spreadsheet or app to do that?