If you want to do calculations based on cells containing times you need to use the TIME and TIMEVALUE functions.

Add 1 hour to time

You can’t simply use =A1+1 to add an hour to a time stored in A1, you need to define which part of the time value – hh:mm:ss – you want to add one to. You must define the value as TIME then use hh,mm,ss options for the value to add

A B < B function >
1 04:00 05:00 =A1+TIME(1,0,0)
2 04:00 04:30 =A2+TIME(0,30,0)

Show a time range using a cells time as starting point

Use CONCATENATE or & to add free text (“~”) between the time from an existing cell and existing cell +3 hours

A B < B function >
1 04:00 04:00~07:00 =CONCATENATE(TEXT(A1,”hh:mm”),”~”,TEXT(A1+TIME(3,0,0),”hh:mm”))
2 04:00 04:00~07:00 =TEXT(A2,”hh:mm”)&”~”&TEXT(A2+TIME(3,0,0),”hh:mm”)

If time in cell is less than defined time minus one day

If you want to use time from a reference cell in a function you have to use TIMEVALUE
e.g. if time in column A cell is less than 01:00, take date from column B cell and -1 day, else leave same value as column B cell

A B C < C function >
1 12:30 AM 10/06/2016 09/06/2016 =IF(A1>=TIMEVALUE(“01:00 AM”),B1,B1-1)
2 02:00 AM 10/06/2016 10/06/2016 =IF(A2>=TIMEVALUE(“01:00 AM”),B2,B2-1)
3 01:00 AM 10/06/2016 10/06/2016 =IF(A3>=TIMEVALUE(“01:00 AM”),B3,B3-1)

Also see