First of all, the format for milliseconds are

hh:mm:ss.000

secondly, you can use

=average(time_range)

to display results you can use

[hh]:mm:ss.000

which will take care of hours over 24

so to type in your example use

00:05:78.98

otherwise you'll get text and it can't be used for any calculations

Regards,

Peo Sjoblom

"LKP" wrote:

I'm trying to work with time. I'll be adding and averaging many different
process times for a business project. How do I format these times and write
a formula? The tricky part is the times are all the way to milliseconds.
The format is 00:00:00:00 in hh:mm:ss:ms. Say I have 00:05:55:78 and
00:04:34:98. How do I add these and then also get an average of the two??
I've been stuck with this problem for a while. Version 2003 Excel.