Free online countdown calculator

How to use

1. Enter your target date and time using the datetime input.
2. The countdown starts immediately and updates every second.
3. Press “Share with my numbers” to copy a link with your target pre-filled.

How the countdown works

Each second the calculator computes the difference between the target datetime and the current moment (Date.now()). It breaks the total number of remaining seconds into days, hours, minutes, and remaining seconds:

• Days: total seconds divided by 86,400, floored.
• Hours: remaining seconds after removing whole days, divided by 3,600, floored.
• Minutes: remaining seconds after removing whole hours, divided by 60, floored.
• Seconds: remainder after removing whole minutes.

When the target is in the past, all values reflect how much time has elapsed since the target, and a notice is shown.

Worked example

Target: December 31, 2025 at 23:59:00 local time. Current time: April 19, 2026 at 12:00:00.

Since the target is in the past, the calculator shows elapsed time: roughly 109 days, 12 hours, 1 minute, 0 seconds since that moment.

Notes

• The countdown is driven by your device clock. If the device clock is inaccurate, the countdown will be off by the same amount.
• The page must remain open for the countdown to tick. It does not run in the background.
• Daylight saving time transitions may cause a one-hour jump if the target spans a DST change. This is expected behavior from the browser’s local-time arithmetic.