Inclusive and exclusive day counting
A difference measures the gap
The ordinary date difference from October 1 to October 4 is three days. It measures the number of day boundaries between the dates.
Inclusive counting includes both dates
If a booking or activity includes October 1, 2, 3 and 4, the inclusive count is four. Choose the convention that matches the task and state it clearly.
Rules may add other conditions
Business-day deadlines can exclude weekends or holidays and may have special cutoff times. RSDateSpan does not apply those rules; it reports a calendar count using the selected convention.
Try the workflow
October 1 to October 4 is a three-day difference. Counting both calendar dates inclusively gives four days.
Open date difference calculator