Hi Biff

I don’t recognise any lack of robustness in the formula I posted. It
does exactly what I said it would, which is to give the total business
hours between the two time/dates, based on a 9 hour day (with no meal
break) and assuming the start and end times both fall within those
business hours

I think the meal break problem here clouds the issue, I see what you
have attempted to do with the formula you posted but it means that in
some circumstances a later end time/date can result in a shorter time
period returned, e.g.

A1 = 25 Apr 06 09:00, B1 = 27 Apr 06 16:30 24.5

A1 = 25 Apr 06 09:00, B1 = 28 Apr 06 08:15 24.25

Your formula also gives some strange results in other circumstances

A1 = 25 Apr 06 09:00, B1 = 25 Apr 06 10:00 10

Surely this should be 1 hour not 10?

If start/end times outside business hours ARE to be allowed then, again
assuming a nine hour day, from 08:00 to 17:00 and B1 not less than A1,
I’d suggest this formula.

=(NETWORKDAYS(A1,B1,)-1)*9+IF(NETWORKDAYS(B1,B1),MEDIAN(MOD(B1,1)*24,17, 8),17)-IF(NETWORKDAYS(A1,A1),MEDIAN(MOD(A1,1)*24,17,8),8)


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