Excel formula or VBA Identifying gaps in overlapping dates and times

[TreeStone]

I am attempting to find any gaps between a start and stop date/time range. Essentially time when there are no appointments in the schedule, this is a 24hr service and I am looking for "dead" time when there isn't a customer in the office.

Currently I was attempting to use the =SUMPRODUCT((A2<B$2:B$19)*(B2>A$2:A$19))>1 to find overlaps and the issue I am running into is if there are any overlap in start or stop it disqualifies and does not truly identify the space between appointments just if that appointment is double booked at all.

Standby Example.xlsx
	A	B	C	D	E
1	Enc Registration Dt/Tm	Enc Discharge Dt/Tm	SUMPRODUCT	Formula	Gaps in appointments by minute
2	Jan 1, 2022, 3:30 AM	Jan 1, 2022, 4:15 AM	FALSE	SUMPRODUCT((A2<B$2:B$19)*(B2>A$2:A$19))>1	-196
3	Jan 1, 2022, 7:31 AM	Jan 1, 2022, 8:35 AM	TRUE	SUMPRODUCT((B3<C$2:C$19)*(C3>B$2:B$19))>1
4	Jan 1, 2022, 8:25 AM	Jan 1, 2022, 10:37 AM	TRUE	SUMPRODUCT((B4<C$2:C$19)*(C4>B$2:B$19))>1
5	Jan 1, 2022, 8:30 AM	Jan 1, 2022, 11:48 AM	TRUE	SUMPRODUCT((B5<C$2:C$19)*(C5>B$2:B$19))>1
6	Jan 1, 2022, 8:35 AM	Jan 1, 2022, 11:40 AM	TRUE	SUMPRODUCT((B6<C$2:C$19)*(C6>B$2:B$19))>1	-158
7	Jan 1, 2022, 2:17 PM	Jan 1, 2022, 5:01 PM	TRUE	SUMPRODUCT((B7<C$2:C$19)*(C7>B$2:B$19))>1
8	Jan 1, 2022, 2:44 PM	Jan 1, 2022, 6:04 PM	TRUE	SUMPRODUCT((B8<C$2:C$19)*(C8>B$2:B$19))>1
9	Jan 1, 2022, 2:49 PM	Jan 1, 2022, 5:15 PM	TRUE	SUMPRODUCT((B9<C$2:C$19)*(C9>B$2:B$19))>1
10	Jan 1, 2022, 2:54 PM	Jan 1, 2022, 5:34 PM	TRUE	SUMPRODUCT((B10<C$2:C$19)*(C10>B$2:B$19))>1
11	Jan 1, 2022, 5:30 PM	Jan 1, 2022, 6:43 PM	TRUE	SUMPRODUCT((B11<C$2:C$19)*(C11>B$2:B$19))>1
12	Jan 1, 2022, 5:55 PM	Jan 1, 2022, 9:29 PM	TRUE	SUMPRODUCT((B12<C$2:C$19)*(C12>B$2:B$19))>1
13	Jan 1, 2022, 8:53 PM	Jan 1, 2022, 10:25 PM	TRUE	SUMPRODUCT((B13<C$2:C$19)*(C13>B$2:B$19))>1
14	Jan 1, 2022, 9:26 PM	Jan 2, 2022, 12:29 AM	TRUE	SUMPRODUCT((B14<C$2:C$19)*(C14>B$2:B$19))>1
15	Jan 1, 2022, 10:01 PM	Jan 1, 2022, 11:45 PM	TRUE	SUMPRODUCT((B15<C$2:C$19)*(C15>B$2:B$19))>1
16	Jan 1, 2022, 10:50 PM	Jan 1, 2022, 11:31 PM	TRUE	SUMPRODUCT((B16<C$2:C$19)*(C16>B$2:B$19))>1	-7
17	Jan 1, 2022, 11:38 PM	Jan 2, 2022, 1:53 AM	TRUE	SUMPRODUCT((B17<C$2:C$19)*(C17>B$2:B$19))>1
18	Jan 1, 2022, 11:42 PM	Jan 2, 2022, 6:23 AM	TRUE	SUMPRODUCT((B18<C$2:C$19)*(C18>B$2:B$19))>1
19	Jan 1, 2022, 11:50 PM	Jan 2, 2022, 1:56 AM	TRUE	SUMPRODUCT((B19<C$2:C$19)*(C19>B$2:B$19))>1
Sheet1

Cell Formulas
Range	Formula
E2,E16,E6	E2	=(B2-A3)*1440
C2:C19	C2	=SUMPRODUCT((A2<B$2:B$19)*(B2>A$2:A$19))>1