Help with formula 09:30-10:00

Departure should be 10:00 however it left earlier by 30mins. How is it formulated please?

The question is vague. There’s no need to use terms “Departure”, “left earlier” etc. Instead, please say what you have and want to see in what cells, like:

“I have 10:00 in A1, and 9:30 in B1. I want to see -0:30 in C1. How to do that?”

I am not sure that my interpretation of your question is correct, so please edit your question to make it more specific.

Great! That is exactly what i want to see. Thanks

Then use [HH]:MM format string for C1 with formula =B1-A1.

Also other way around…8:00 in A1 and 8:45 in B1…i want to see 0:45 in c1

Got it. What if it goes next day?
A1 23:00
B1 02:00
C1 03:00

Use dates in A1 and B1.

I just tried 26:00 instead of 02:00 - looks good. It gave me 03:00…thanks mucho!

sigh… why don’t people want to do it right way, and invent workarounds like “26:00” instead of “2018-02-07 02:00” (optionally formatted as “HH:MM” to only show the time), so that later one could expand or make statistics, and could get sensible result from correct data…