One way:

Dates in XL are stored as integer offsets from a base date, and times
are added/stored as fractional days, so if your date field is in cell
A1, use

=MOD(A1,1)*1440

to get minutes (24 hr/day * 60 min/hr = 1440 minutes/day)

In article ,
MSwan1 wrote:

I want to copy a date field "10/18/2005 8:05" into another column and change
it to a number (minutes) so 8:05 (8 hours & 05 minutes) reads as 485 minutes
- and I would take the 485 and divide it by another value to yield gallons
per minute.

The date field is downloaded from another source so I cannot change it's
format direcetly. How do I change it after I copy it into a number format?