This is only an example that you can adapt to your needs. The job involves placing 600 large blocks. We initially assume that we can place 3 blocks per day. The job started April 1st. In A2 we enter:
In B2 we enter the formula:
=A2+600/3 our initial estimate of the end date.In C2 we enter today's date and in D2 we enter the total progress to date. (Both C1 and D1 can be updated daily.)
In D3 we enter the formula:
=D2/600 This is our percent complete.
In E2 we enter a formula to re-evaluate the productivity based on actual data:
Finally in F2 we can enter our latest, best, estimate of the completion date:
=TODAY()+(600-D2)/E2 Here is a sample:
In this sample, we initially thought it would take 200 days to place the blocks. We now see that the actual productivity is only around 2.2 compared to 3.0 This allows us to re-estimate the completion date based upon the actual productivity and the number of blocks that still must be placed.