Countdown Calculator
Pick a date and a time and watch the time remaining tick down, second by second. The page shows the days, hours, minutes and seconds left, the same span in weeks and in calendar months, and how long ago the moment was if it has passed.
Midnight at the start of the day by default. Your device’s local time.
Countdown
Pick a date to start the countdown.
The calculation runs in this browser tab. Nothing you enter is uploaded, saved or logged.
How does a countdown to a date work?
A countdown is the difference between two moments: now and a target. The calculator reads your device’s clock once a second and subtracts it from the target date and time, then splits the remaining seconds into days, hours, minutes and seconds. If the target is in the past it shows the same figures as time elapsed since it.
The span can be read in several ways. “187 days 12:00:00” is the exact elapsed time. The calendar breakdown (for example 6 months and 5 days) counts whole months on the calendar from today’s date, and is easier to picture. Both describe the same gap; they differ because months are not all the same length.
How to use the Countdown Calculator
- Optionally name your event, for example “Summer holiday”. The name is only displayed on the page.
- Choose the target date and, if you need it, the time. It defaults to midnight at the start of that day.
- Read the countdown. It updates every second while the page is open.
- Look at the details for weeks, calendar months and totals, and use Copy result to copy a sentence with the current countdown.
Formula
- Remaining seconds
- S = days between × 86,400 + (target time − current time) in seconds
- Days and clock
- days = ⌊S ÷ 86,400⌋; hours = ⌊(S mod 86,400) ÷ 3,600⌋; minutes and seconds follow
- Weeks
- weeks = ⌊days ÷ 7⌋, with days mod 7 left over
The calendar breakdown uses dates only: whole months from today’s date to the target date, then the leftover days.
If the target time is earlier in the day than the current time, one day is borrowed, so the days shown can be one less than the difference between the two dates.
Worked example
Counting down to Christmas Day. For this example the current moment is fixed at 12:00 on 20 June 2024; on the page it follows your clock. These are the figures it gives:
| Question | Result |
|---|---|
| Input: Current date and time (for this example) | Thursday, 20 June 2024, 12:00 |
| Input: Target | Wednesday, 25 December 2024, 00:00 |
| Time until the target | 187 days 12:00:00 |
| In weeks | 26 weeks and 5 days |
| By the calendar | 0 years, 6 months, 5 days (dates only) |
| Total hours | 4,500 |
Assumptions and limits
- Time is read from your device’s clock and local time zone. If your clock is wrong, the countdown is too. Nothing is sent to a server.
- The target is a local time, not a moment in a specific time zone. To count down to an event in another time zone, convert its time to yours first.
- Daylight-saving changes are not applied: if the clocks change between now and the target, the real elapsed time differs from the figure by an hour.
- The countdown only runs while the page is open and updates once a second. Browsers may slow the updates of background tabs.
- Dates run from year 1 to year 9999.
Frequently asked questions
How many days are left until a date?
Pick the date and read the days at the top; the time of day matters, so the figure can be one less than the difference between the two dates until the target time has passed on the final day. For example, at noon, midnight tomorrow is 0 days 12:00:00 away.
Does the countdown update in real time?
Yes, once a second while the page is open. It uses your device’s clock, so it keeps running without any connection once the page has loaded.
What happens when the date has passed?
The page switches to “time since” and shows how long ago the moment was, with a note that it has already passed. You can then set a new target.
Can I count down to an event in another time zone?
Not directly: the target is a local time. Convert the event’s time to your own time zone, and enter that. For example, a 15:00 start in New York is 20:00 in London when both are on standard time.
Why does the calendar breakdown differ from the days shown?
The calendar breakdown counts whole calendar months, which have 28 to 31 days, while the exact figure counts seconds. Both are correct; the calendar one is easier to picture and the exact one is what a stopwatch would show.
Are daylight-saving changes taken into account?
No. If the clocks go forward or back between now and the target, the real time left differs by an hour from the figure shown. For a long countdown, check it again on the day.