Countdown Timer
Pick a date and time to count down to — it ticks live, down to the second.
How Countdown Timer Works
This countdown timer counts down live to any date and time you pick -- a birthday, deadline, event, or launch -- showing days remaining as the headline number, with hours, minutes, and seconds ticking down alongside it every second.
Formula & Method
The calculator takes the difference in milliseconds between your chosen target date/time and the current moment (target − now). That gap is converted to whole days (dividing by 86,400 seconds), with the remainder split into hours, minutes, and seconds using modulo arithmetic, so the four numbers always add back up to the exact remaining gap. This recalculates and redraws once every second for as long as the page stays open. Once the target moment has passed, it displays a "time's up" message instead of a countdown.
Worked Example
If it's currently 3:15:00 PM on a given day and you count down to 6:00:00 PM the same day, the timer shows 0 days remaining, with 2 hours, 45 minutes, and 0 seconds broken out separately -- ticking down second by second until the target time arrives, at which point it switches to an arrival message.
Frequently Asked Questions
- Does the countdown keep running if I leave the tab open?
- Yes -- the timer recalculates the remaining time once per second for as long as the page stays open in your browser, so the display stays accurate to the second without needing a page refresh.
- What time zone is the countdown based on?
- The target date and time you enter is interpreted in your device's local time zone, and the countdown compares it against your device's current local time -- so the timer will count down correctly regardless of which time zone you're in.
- What happens when the countdown reaches zero?
- Once the target date and time has passed, the display switches from a day/hour/minute/second countdown to an arrival message using the event name you entered (or a generic "Time's up!" if no name was given).
- Can I name what I'm counting down to?
- Yes -- the optional Event Name field lets you label the countdown (e.g. "My Birthday" or "Product Launch"), and that name is then used in both the running countdown label and the completion message.