Creating a Pipe Tally and wish to record time taken from one entry to the next. Using Excel 2016 to enter data by depth and record a Timestamp at each entry. I then want to calculate the time difference from the current depth entry to the previous. I have 4 Columns. Hole Depth Column, Kelly Down Column, Timestamp Column & a Time Diff. Column. The problem I am trying to solve is calculating the time diff between non consecutive Timestamp rows. Ex..

Pipe Tally Auto Time Stamp:

How do I calculate this?

Is there a PREVIOUS Time function that could be utilized here?

I only know how the calculate a time difference using a specified cell. Hence the calculation I am using only calculates from the one cell directly above it. Not two or even Three.

Calculates from one cell to the next only: