Days Until Calculator
How many days until Christmas? Until your vacation? Until your exam? This calculator takes any target date you enter and subtracts today's date to give you the exact number of calendar days remaining. It uses midnight-to-midnight day counting, so the result reflects complete days remaining. The result also shows weeks and days as a convenient breakdown. Enter any date to get your countdown.
Days until formula
Days = (Target date at midnight) - (Today at midnight), in days
Multiply millisecond difference by 1/(1000 * 60 * 60 * 24) and round. For example, if today is June 15, 2026 and your target is December 25, 2026, the result is 193 days (6 weeks and 31 days, or 27 weeks and 4 days).
Popular countdowns in the US
- Christmas Day: December 25
- New Year's Day: January 1
- Independence Day: July 4
- Thanksgiving: fourth Thursday of November
- Halloween: October 31
- Tax Day: April 15 (or next business day if weekend)
Days until: frequently asked questions
How is the days until count calculated?
The calculator subtracts today's date from your target date, dividing the difference in milliseconds by the number of milliseconds per day (86,400,000) and rounding to get whole calendar days.
Does it count the start date or end date?
The count is the number of full days from today (midnight) to your target date (midnight). Today itself is not counted; if your event is tomorrow, the result is 1.
Can I use this for past dates?
If you enter a date in the past, the calculator will return a negative number showing how many days ago that date was.
Does the result account for time zones?
The calculator uses your browser's local midnight as the reference, so it reflects your local calendar date. A date that is tomorrow in New York may already be today in Los Angeles.
What common events is this useful for?
Countdowns are commonly used for holidays (Christmas, New Year's Day, July 4th), vacations and travel, exam dates, contract deadlines, product launch dates, sporting events, and personal milestones such as anniversaries and weddings.
Official sources
- U.S. Office of Personnel Management, federal holiday schedule: opm.gov federal holidays.
- U.S. Naval Observatory, time services: aa.usno.navy.mil.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.