Time formulas are acting wonky

Have you checked the time in column D? It's probably showing as 12:30:00 while then in in column F is 12:30 (text and not a real time value).

Another simple comparison in colum E place the formula =D5=F5 you'll notice right away

You fell for the same misconception as do many Excel users.
What you see in a cell (when it's formatted) is the formatted result, so if I place 23.668 in a cell and format is as 0.00 the value you SEE is 23.69 so if you enter 23.69 in the cell next to it and us use conditional formatting to color the cell if the value is equal to the other one it is not. because 23.69 is NOT equal to 23.688

In addition to the rounding "error" that Keebellah notes, there is also the potential for "floating point" error when dealing with times (especially calculated times). Remember that, to Excel, time is just a floating point double precision number between 0 and 1, which means that it is subject to floating point errors. You may need to consider this possibility and adjust your algorithm to account for these errors (usually some kind of ROUND() function).

More than you probably ever wanted to know about floating point errors: https://www.excelforum.com/groups/ma...nd-errors.html

It seems nobody is listening.
Good-night then
It's bed-time here

This should be easy enough to sort out. Can you post a workbook so we can take a look?

The forum rules explain how.

Definitely looks like floating point error. I formatted your time cells as "0.00000000000000000" instead of time and expanded the columns so I could see all digits. Sure enough, in all "no work" cases, there was a difference in the last digit/bit. As I noted, the usual solution is to use a ROUND() function IF(ROUND(D4,6)=ROUND(F4,6),...) or an ABS(difference) test IF(ABS(D4-F4)<1E-6,...) or some other strategy that will capture and ignore this insignificant difference.

I added conditional formatting with the way I see it and your MOD formula
I've run into this so many time.
NOW I'm off to bed.
Bye for now.

If it seems odd to you, then be sure to review some of those links about floating point issues. This is and has been a universal issue for computers doing arithmetic since the beginning, and will continue to be a part of computer arithmetic. If you are going to be doing these kinds of calculations, you need to be aware of how floating point issues can impact the calculations and how to work around them.

I'm quiet aware of floating point issues but this is a check of difference in tow time values which are hh mm ss and if you compare an entered value manually Excel automatically makes it hh:mm:ss even IF you enter only the hours and the minutes.
The other column is a result and does NOT contain a seconds value, maybe 01 second so 12:30:00 IS different to 12:30:01.9999 or whatever and the OP is staring blind at the FORMAT of the cell not the value.
So that is all I did in the conditional formatting.
This will not be resolved by the floating point issue or whatever and the floating point issue is of severe importance to critical calculations as flight plans or measurements but the comparison for a visual difference has nothing to do with that.

If you change F6 to

=MROUND(F7 - "0:15", "0:01")

it works fine.

You fly out of Lemoore?

Time formats and all the same as goes for values