The brackets tell to Excel the time is a duration, and not a time of day.
Note: to use square brackets, you’ll need to create and apply acustom number format.
Select cells, then go to Format Cells (Control + 1) > Number > Custom.
Convert decimal seconds to Excel time
To convert seconds in decimal format to a proper Excel time, divide by 86400. In the example shown, the formula in C6 is: =B6/86400 To display the result as time, apply a time format. Column D shows the same result formatted with [h]:mm.
