Calculating start and times

I am new to Airtable trying to set up a duty roster which includes an input for start and finish times that calculates the differs in the duration field. Would I use DATETIME_DIFF({Finish Time}, {Start Time},‘seconds’) to calculate? I would like to manually input my start and finish times as well. Thanks.

Start Finish ** Duration**
6:55AM 7:40AM 0:45

Yes, that’s the way.

Thanks for the feedback.