Frequently asked questions
Does "Days between dates" include the end date?
By default it calculates the difference (End − Start), matching standard subtraction and hotel-night rules. Enable "Include end date in count (+1 calendar day)" when both start and end dates are full active days.
What happens if my start date is later than my end date?
The calculator automatically detects reversed chronological order, displays the exact positive duration, and notes that the end date precedes the start date (or click "Swap dates" to flip them).
How are working (business) days calculated?
Every Monday through Friday in the date span counts as 1 working day, while Saturdays, Sundays, and any valid weekday dates listed in your custom holidays field are excluded.
How does adding 1 month to January 31 work?
When adding calendar months lands past the end of a shorter month (such as February), the date clamps cleanly to the final valid day of that month (February 28, or February 29 in a leap year).
Are leap years handled automatically?
Yes. All calculations use Gregorian calendar rules including 366-day leap years.
Does timezone or Daylight Saving Time change the day count?
No. Dates are evaluated using timezone-neutral UTC calendar days so local clock shifts never alter day counts.