Use Time Calculator to calculate the time subtraction between 2 times:
↪ You can enter a time in the past and subtract it from the present time: You get the elapsed hours and minutes.
↪ You can enter multiple time in list: You get the elapsed hours and minutes of each time entry and you can get the total elapsed hours and minutes.
↪ You can enter a date, past time and present time: You get the elapsed hours and minutes.
↪ You can add and save the multiple date and time as entry in phone: You get the elapsed hours and minutes of each time entry and you can get the total elapsed hours and minutes for entries you want.
↪ You can delete saved entries.
↪ You can export entries.
↪ You can import entries.
↪ You can clear all entries.
↪ You can get total entries.

Example:
✓ 10:00 AM to 06:45 PM = 08 hours 45 minutes
✓ 01:00 PM to 06:50 PM = 05 hours 50 minutes
✓ 29/10/2018, 10:00 AM to 06:45 PM = 08 hours 45 minutes
✓ 30/10/2018, 01:00 PM to 06:50 PM = 05 hours 50 minutes
✓ 08 hours 45 minutes + 05 hours 50 minutes = 14 hours 35 minutes and total entries calculated

⇒ Note: Future time unit can't be subtracted from past time unit i.e. can't subtract PM from AM as it is a day change. Example: 10:00 PM to 06:45 AM = 00 hours 00 minutes