It depends on what you are measuring. Use the exclusive count (do not include the end date) when you are measuring elapsed time, like 'days until launch' or 'days since I quit smoking', because the end date has not yet been fully lived. Use the inclusive count (include the end date) when both endpoints are part of the period being counted, such as vacation days you are paid for or contract days you are billed for. The inclusive total is always one more than the exclusive total.

Calendar days count every day on the calendar including Saturdays and Sundays. Business days, sometimes called working days, count only Monday through Friday. A seven-day calendar span typically contains five business days. Most legal, banking, and shipping deadlines are stated in business days, so a contract that says 'within 10 business days' usually translates to about two calendar weeks. Public holidays are not automatically excluded by this counter, so subtract them manually if your jurisdiction observes them.

Pick the milestone you care about and enter it as your end date, or watch the running total grow. The 100-day mark is popular in habit formation and political administrations because it is long enough to show real progress but short enough to stay focused. The 365-day mark celebrates a full annual cycle through every season and holiday, and 1,000 days is a common sobriety and recovery landmark. The counter shows weeks and total days, so you can spot these milestones at a glance.

Yes. Set the start date to today (2026-05-15) and the end date to your target event, such as a wedding, exam, vacation, or product launch. The counter then tells you how many days remain. If you want a live ticking countdown, refresh the page each day or set the start date to roll forward. This pattern is commonly used by wedding planners, pregnancy week trackers, and lease or contract deadline reminders.

The counter uses the proleptic Gregorian calendar, which is the international civil calendar standardized in 1582 and extended backward by ISO 8601. All months, leap years, and century rules follow Gregorian conventions, so February 2024 has 29 days, 2000 was a leap year, and 1900 was not. Dates before October 15, 1582 fell under the older Julian calendar in most of Europe; you can still enter them, but the day count will follow Gregorian arithmetic and may differ from historical records by a few days.