Countdown Calculator (Days Until)
Live countdown to any future date — days, hours, minutes, and seconds. Great for birthdays, holidays, vacations, and project deadlines.
What this calculates
A countdown shows exactly how much time remains until a target date — useful for birthdays, vacations, weddings, project deadlines, and motivation milestones. This calculator updates every second so the numbers always reflect the present moment relative to your chosen target.
Formula & how it works
Time remaining = target_datetime − now_datetime. Break into days, hours, minutes, seconds: days = floor(ms ÷ 86 400 000), hours = floor((ms mod 86 400 000) ÷ 3 600 000), and so on. If the target is in the past, return zeros.
Worked example
Today is 2026-05-15, target is 2026-12-25 (Christmas). Remaining = 224 days, 0 hours, 0 minutes, 0 seconds. If target is 2026-05-16 09:00, remaining might be 18 hours, 23 minutes, 12 seconds depending on the moment you check.
Frequently asked questions
Does the countdown update in real time?
Yes, every second. Closing or reloading the page resets the display from the new current time but the target date stays the same.
Can I share a countdown?
Copy the URL after picking your date — query parameters preserve the target so anyone opening the link sees the same countdown.
What time zone is used?
Your browser's local time zone. If you set a target of '2026-12-25 00:00' and you're in New York, that's New York midnight. Adjust if you're targeting a different zone (e.g., a flight or live stream).
What happens after the target date?
The countdown shows zero. You can change the target to a new date to start a new countdown.