Countdown to a Date Calculator

How the countdown works

There are two numbers on a countdown, and they answer slightly different questions. The headline is the number of calendar days from today's date to the target date. It is found by turning both dates into serial day numbers and subtracting, so it is an exact whole number and does not change during the day — at 8 a.m. and 11 p.m. on Monday, Friday is still four days away.

The live clock underneath counts the exact time remaining to midnight at the start of the target date, or to the time you enter, using your device's clock and time zone. It updates every second. Because it measures real elapsed time, a daylight-saving change between now and the event shifts it by an hour relative to a naive count; the calendar-day figure is unaffected.

calendar days = serial(target) − serial(today)
live clock = target moment − current moment, shown as days, hours, minutes, seconds

Worked examples

Example 1: days until a holiday

On 20 October 2026, the countdown to 25 December 2026 is 66 days: 11 days left in October, 30 in November and 25 in December. That is 9 weeks and 3 days, with 48 weekdays and 18 weekend days.

Example 2: a flight at a set time

Enter 2026-11-26 and 06:45. The headline shows the calendar days, while the live clock counts down to 6:45 a.m. local time on that morning, which is the figure to watch on the day itself.

Example 3: a date in the past

Enter a date that has already passed and the headline switches to "days ago", which is handy for streaks: how many days since you started a habit, quit smoking or launched a project.

How to read the result

The large figure is calendar days to go. Below it you get the same span in weeks and days and in years, months and days. The four boxes are the live clock. The table splits the remaining days into weekdays and weekend days — useful for planning work or school days before a deadline. Public holidays are not removed, because they vary by country and employer. If you named the event, the name appears in the heading so a screenshot makes a tidy reminder.

Is today counted?

No. The count runs from today to the target, so tomorrow is 1 day away and the target date itself shows "Today is the day". This matches how people usually speak ("three sleeps until Christmas" on 22 December). If you want to know how many dates are on a calendar between now and an event including both ends, add one, or use the days between dates calculator with its inclusive option.

Common uses

Countdowns help with motivation and planning: days until a wedding, holiday, exam or due date; the number of weekdays left to finish a project; how long until a visa, lease, passport or warranty expires; or how many days are left in a challenge. Teachers count school days to the end of term, and event organisers count weeks to work back through a schedule. To find the date a number of days from today rather than the days to a date, use the add or subtract days calculator, and for birthdays the age calculator includes its own next-birthday countdown.

Time zones and the live clock

The live clock targets the time you enter in your device's current time zone. If the event happens elsewhere — a product launch at 9:00 in New York watched from London — convert the event time to your local time first, or set the time to match. The calendar-day count is based on your local date, so near midnight it can differ by one from a friend's count in another time zone. If you leave the page open, the clock keeps ticking; pressing Calculate again refreshes the whole result.

Limits

Dates from year 100 to 9999 get a live clock; earlier years still show the calendar-day count. The countdown relies on your device's clock being right, which it almost always is when it syncs to network time. It does not account for leap seconds, which are not used by ordinary device clocks. Weekday counts use a Saturday–Sunday weekend. Nothing you enter is stored; bookmark the page or note the date if you want to check again later.

Sharing a countdown

The result is designed to screenshot cleanly: the event name, the target date in words and the number of days appear together at the top. Because counts are based on each viewer's own date, anyone who opens the page and enters the same date will see the figure for their day.