Countdown Timer

About the Countdown Timer

Set a date and time and watch the days, hours, minutes and seconds tick down. Give the event a name, choose the time zone it happens in, and share a link: anyone who opens it sees the same countdown, with the moment converted to their own time zone.

The clock is calculated from the exact target moment and your device’s clock, so it stays correct when you switch tabs, lock your phone or leave the page open for days. When it reaches zero it can play a sound and show a notification. If the date has already passed, it shows the time since instead.

Common uses

• Counting down to a product launch, sale, exam, wedding or holiday.
• Sharing an event time with people in other countries without converting time zones by hand.
• Showing a full-screen countdown on a TV or projector at an event or in a classroom.
• Checking exactly how long ago something happened.

How the countdown stays accurate

The time left is recalculated from the target moment and your device’s clock every time the screen refreshes, instead of counting ticks. Background tabs, sleeping laptops and locked phones therefore cannot make it drift: when you come back, it is right immediately.

It can only be as accurate as your device’s clock. Phones and computers normally set their clocks automatically from the network; if yours is set by hand and is a few minutes off, the countdown will be too.

Time zones and daylight saving

Time zone rules come from the IANA time zone database built into your browser, so daylight-saving changes are applied for the date you pick, not just for today.

• A time that does not exist because the clocks go forward (for example 02:30 on 8 March 2026 in New York) is moved forward by the size of the gap, and you are told.
• A time that happens twice because the clocks go back (01:30 on 1 November 2026 in New York) uses the first occurrence, and you are told.

Link format

A countdown link has up to three parameters:

• to — the date and time, such as 2026-12-31T23:59 (seconds are optional). An exact moment with an offset, such as 2026-12-31T18:29:00Z, also works.
• tz — the IANA time zone, such as Asia/Kolkata or America/New_York. Without it, the viewer’s own zone is used.
• title — the event name, shown as plain text (up to 80 characters).

For example, to=2027-01-01T00:00, tz=Asia/Kolkata and title=New+Year+2027 together make a New Year countdown for India. Copy link builds the link for you.

Limitations

• Sounds and notifications only happen while this page is open. Phones may pause pages in the background, so an alert can arrive late, when you return to the page.
• Browsers only play sound after you have clicked or tapped on the page. If you open a shared link and want a sound, press Test once.
• Some browsers, for example Safari on iPhone, only allow notifications from web apps added to the home screen.
• Dates from the year 1000 to 9999 are supported. For dates before 1970, time zone offsets may be less reliable: the time zone database only aims to be accurate from 1970 onwards.

Privacy

The countdown runs in your browser, and your last countdown is remembered only in this browser. If you share a link, the date, time zone and event name are part of the web address, so anyone with the link can read them — do not put private details in the event name.