Hi,
Try this formula in label text property

RoundDown(DateDiff(DatePicker1.SelectedDate, DatePicker2.SelectedDate, TimeUnit.Days) / 7, 0) * 2 +
If(Weekday(DatePicker1.SelectedDate) = 1, 1, 0) +
If(Weekday(DatePicker1.SelectedDate) = 7, 1, 0) +
If(Weekday(DatePicker2.SelectedDate) = 1, 1, 0) +
If(Weekday(DatePicker2.SelectedDate) = 7, 1, 0)
Thanks!
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