Millisecond Clock for Ticketing (Server-Synced)

A large clock that shows standard time to the millisecond, corrected with this site's server time, with a countdown and alert sounds for the moment a ticket sale, course registration or limited release opens. It also shows how far your own device's clock is off.

How to use

1. Open the page and wait a few seconds. The clock checks the time with the server and shows "Standard time from the server" with its accuracy, and how far "This device's clock" is off.
2. Under "Time zone", choose the zone where the sale takes place, for example "Japan (Tokyo)" or "US Eastern (New York)". The clock and the target follow that zone.
3. Switch on "Count down to a time", enter the opening time in "Target date" and "Target time" (or press "Next full hour"), and set "Act early by" if you want zero to come a little earlier.
4. Under "Alerts and screen", choose "Short beeps from" and the "Volume", then press "Test sound" once so the browser allows sound.
5. Press "Full screen" or the F key for big digits. "Keep the screen on" stops the screen from turning off where the browser supports it.

How it works

• Correction: the page asks this site's server for the time several times, keeps the answers with the shortest round trip and assumes the answer was made halfway through that round trip. Accuracy = half of the round trip.
• The clock resyncs every 5 minutes, when you return to the tab and when you press "Sync now". In the last minute before zero it does not resync, so the count does not jump.
• If the server cannot be reached (offline, or the page was opened from a copy), the clock shows the device's own time and says so on screen.
• Settings are saved only in this browser. The only thing sent is the short time request to this site's server.

Why a sale may open slightly earlier or later than this clock

This clock shows standard time. A ticket or registration site decides the opening by its own server clock, which this page cannot read. That clock is usually close to standard time but can differ by a fraction of a second or more.

Some sites also open in stages, put visitors in a queue, or open by hand. Use the countdown to be ready, and watch the ticket site itself at the moment of opening.

Network delay and "Act early by"

Every message on the internet takes time to travel. When the page asks for the time, the answer is already a little old when it arrives. The page measures the round trip and corrects for half of it; the shorter the round trip, the smaller the ± value.

Your click on the ticket site also needs time to reach its server, usually a small fraction of a second and often more on mobile networks. "Act early by" moves the countdown zero and the alert sounds earlier by the number of milliseconds you enter, from 0 to 1000.

Device clock, sound and screen

Phones and computers keep their own clock and correct it from time to time. A device clock that is a few tenths of a second off is common. The panel under the clock shows how far yours is off; turning on automatic time in your device settings reduces the gap.

The alert sounds are scheduled in advance on the audio clock, so they play on time even if the page is busy. Bluetooth speakers and headphones can add a delay. Keep the tab in front, because browsers may slow down background pages.

Questions and answers

Is this clock the same as the ticket site's server time?

Not necessarily. It shows standard time from this site's server, corrected for network delay. A ticket site's server usually runs close to standard time but can differ by a fraction of a second or more.

What does "±18 ms" mean?

It is the accuracy of the correction: the true time is within 18 milliseconds of the clock. It is half of the fastest round trip to the server, so a faster connection gives a smaller number.

My device clock is 0.4 seconds fast. Do I need to fix it?

This page corrects it while the sync works. Turning on automatic time in your device settings also helps other apps and countdowns on other sites.

How many milliseconds early should I click?

There is no fixed number, because network delay and the ticket server's clock vary. "Act early by" lets you choose 0 to 1000 ms; it moves only the countdown and the sounds on this page.

Why is there no sound?

Browsers block sound until you tap the page. Press "Test sound" before the sale and check the device volume and silent mode.