Timer, stopwatch and countdown

1. 01Choose at the top: Timer (counts down a duration), Stopwatch (measures with laps) or Countdown (to a day and a time). All three keep running, even when you switch between them.
2. 02For a timer, type a name if you like, then tap or type a duration. It starts right away. Up to five timers run at the same time.
3. 03“Full screen” shows the time large, easy to read from a few meters away. The address remembers the tab you chose, for example bnkz.de/en/calculator/timer/#stoppuhr for the stopwatch.

Typing a duration: A number alone means minutes (7 or 2.5). With a colon it is minutes and seconds (7:30), with two colons hours, minutes and seconds (1:30:00). “1:30 h” is one and a half hours. Units work too: 90 s, 5 min, 2 h, 1 h 30 min or 1h30. With a period and two digits after it (1.30) the tool asks what you mean, because that can mean 1:30 or 1.3 minutes. Before the start, the line below the field says in words what the tool understood. At most 99 hours, 59 minutes and 59 seconds.

Accuracy: The page does not count ticks. It compares the clock of the browser with the start time. That is why the time is right even when the tab is in the background and the browser slows it down. The display then only moves on when you look at it again. If a laptop or phone sleeps with the tab open, the page adds the sleep time after waking up: the stopwatch then shows the whole time, and a timer goes off immediately, but too late.

Alarm: The browser itself produces the sound (Web Audio), no sound file is loaded. At the start the page already schedules it on the audio clock of the browser. On a computer it therefore usually comes on time even in a background tab. On a phone the system often stops a browser in the background completely. If you hear nothing, check the volume of the device and whether the tab is muted. Most Android phones can vibrate. iPhones and most computers cannot. Also, the browser only vibrates when the tab is visible. The title of the tab flashes until you stop the alarm. If another timer or the countdown rings while the full screen shows a different clock, the alarm appears there with its own “Stop alarm” button.

Keyboard: When an alarm rings, the space bar stops every ringing alarm in the Timer tab and in the Countdown tab. Otherwise, in the Timer tab it starts or pauses the timer you used last (or the only one). In the Stopwatch tab it starts and stops, even when an alarm rings at the same time. R records a lap there. Esc closes the full screen view. If a button or switch is selected, the space bar triggers it, and in an input field it has no effect on the clocks.

Notifications: Only after your click on “Allow notifications” does the browser ask whether the page may show notifications. The page then shows a notification when a timer or the countdown finishes while the tab is not visible. Chrome on Android phones shows notifications of a page only through a background service (service worker). This page deliberately does not use one. There, the sound, the vibration and the flashing title remain.

Keep screen on: The switch asks the browser not to turn off the screen as long as the tab is visible (Wake Lock). This uses battery. If you switch to another tab, the browser releases the lock. When you come back, the page requests it again as long as the switch is on. If your browser cannot do this, the switch stays off.

Stopwatch and laps: “Lap” records the split time. The lap time is the time since the lap before. From two laps on, the fastest and the slowest lap are marked, and in a tie all laps that are equally fast. Times are shown and stored cut off to the hundredth of a second, so the lap times add up exactly to the split time. How precise this really is depends on your finger and on the device: a few milliseconds lie between the tap and the measurement. This is no substitute for timekeeping at competitions.

Countdown and clock changes: The countdown counts the real time until the target. If a clock change (daylight saving time) lies in between, this differs by one hour from what a look at the clock suggests. An example from Germany and most of Europe: from Saturday 12 noon to Sunday 12 noon it is 25 hours on the last Sunday in October, and 23 in March. The tool then tells you when the clocks change. The rules come from the time zone of your device, so the days differ in other countries. A time that does not exist because of the change (in Europe 2:30 in March) is treated like 3:30. For a time that exists twice (in October), the countdown uses the first one. “Nights until then” counts how many more times it will be midnight.

Saving: Nothing is stored in the browser. “Save as file” creates a small JSON file with your timers and the countdown target. Your browser puts it in the downloads folder or asks you where to save it. “Load from file” adds the timers until there are five, and enters the target. You save the laps of the stopwatch as CSV for a spreadsheet.