To subtract time durations and get results in hours or minutes, input your start and end times in two separate cells formatted as 'Time'. Use a subtraction formula like =EndTime-StartTime in another cell. To display the result in hours, format the result cell as 'Custom' and type [h] in the Type field. For minutes, use [m]. This will display total hours or minutes, even if the result exceeds 24 hours or 60 minutes.