Calculation issue with time

[Mindtrap]

I have a calcualtion looking at the difference between 2 times. Everything works great of course unless the second time is after 23:59. As soon as it passes midnight lets say 00:30 I get a huge negative number such as -21.00 Now techically this is correct based of my first entered time. What I want to have happen is I have a departure time of 23:30 and arrival time of 00:30. I want this to give me a value of 1:00 as in one hour, not -23:00 as is 23 hours. I can swear I had this working fine. I posted the spreadsheet on internal work share and somebody entered times and it stopped working. What do I do here?

[NBVC]

Try:

=(B1-A1+IF(B1<A1,1,0)) where A1 contains start time and B1 end time....

format cell as time 13:30