Calendar days, not 24-hour periods
This page counts calendar dates. It does not care what time you woke up. From January 1 to January 31 is 30 days if the end date is excluded, and 31 days if you include it. The checkbox is that choice. Excluding the end date answers “how many days do I step forward to arrive.” Including it answers “how many dates are in the span,” which is what people often want for a trip that starts on the first day and ends on the last. Say which one you mean before you quote the number.
The weekday count is Monday through Friday inside that same span. It does not remove US federal holidays, state holidays, or your employer’s closure list. “Business days” in a contract may mean something stricter. Do not paste this number into a legal deadline without reading the rule that defines the count. The label on the result says weekdays for that reason. A live clock until a single moment is the countdown timer, which is a different question.
Adding days and reading the date
The second box adds or subtracts a number of days from the start date and writes the landing date as a US calendar date: weekday, month, day, year. Adding 30 days to January 1 lands on January 31. Adding 0 stays on the same date. A negative number walks backward. The limit is a very large span so a typo of a million days does not run away. Dates you type use the date field, which your browser shows in your local format. The value underneath is a normal calendar date, not a time zone conversion.
The fields open on a useful example, today’s build date through December 31 of that year, so the page is not blank. Change both dates. If the end is before the start, the totals use the absolute span and the page says so. Order still matters when you add days: addition always starts from the start date, not from the end date. For “how many minutes is this afternoon,” leave this page and open a timer. Days between dates will not ring an alarm.
- Turn on “include the end date” when both endpoints count.
- Weekdays are Monday to Friday only.
- Holidays are not subtracted.
- Add days when you know the length and want the landing date.
What to use this number for
Use it for a trip length, an age of a project in days, the gap between two deadlines, or the date that is 90 days after a start. Then use a timer on the day you do the work. A 25 minute timer is one sitting. A stopwatch tells you how long that sitting was. New Year and Halloween have countdown pages if you want a clock rather than an integer. None of these tools replace the day-count rule in a statute, a court order, or a lease. Read that rule. It may include or skip the start date in a way this checkbox only approximates.