How to calculate the time difference between two time in hh:mm:ss format?

[Emmm]

Dear helpers, 

I'm trying to calculate the time difference between two time in hh:mm:ss format.

Please see the attached excel file for example - Interval column is the result that I need. 

Thank you so much!!!

[Qiu]

@Emmm 
I first add the Date of today to make Date Time format then perform some DateTimeDiff and formula tool to get the format you want.

[Emmm]

Thank you @Qiu !

I tried a similar workflow (please see attached) but i'm not sure why some calculations did not work out as the intervals came out blank? 

The result is in "trial" excel. 

[Qiu]

@Emmm 
It is simply because there are some null values in the column " fvoidtime", so we can not calculate the difference.
You can defind a logic for this case with a filter tool.

[Emmm]

Sorry @Qiu  I think the input I shared was wrong. This input file did not have any null values - but still getting blank intervals... 

[Qiu · Accepted solution]

@Emmm 
We can see that in some of the records, the Void Time is smaller than the Check Open time, meaning the Void Time passed the midnight.
So we should seperate these two cases.

[Emmm]

Thank you so much @Qiu ! I did not realize there are overnight cases causing this issue before... because one of the cases that I were not able to get the result was the second row. Thank you again!!!!   

[Qiu]

@Emmm 
Glad to be helpful. 😁