I have a log file that has a time (hh:mm:ss) in column A, and (among other commands) "LOAD" and "UNLOAD" strings in column B. I need to calculate the total time the machine was idle during the day, i.e., sum the time gaps between each "UNLOAD" command and the next "LOAD" command. I'm not having much luck with simple formulas, and I'm not a VBA programmer. I would appreciate any help.