I consider 7 days to be a week,
so if I look at 1 January 2019 - 7 January 2019,
I would say that is 7 days.
But often I seen when people are calculating the number of days between two dates or age they use the formula
A1 is the Start Date/DoB
B1 is the end date or today's date.
This would give 6 for the above example.
(B1-A1)+1 which gives 7
and for dates of birth I would use
Which is correct?