What is an Online Clock?
An online clock is a clock that runs in your web browser instead of on a wall, watch, or operating-system tray. It uses the time signal already inside your device — synchronized in the background by your OS to internet time servers — and displays it in a large, readable, customizable format. No installation, no account, no syncing of its own. Just open the page and you have an accurate clock.
People reach for an online clock for the same reasons they used to glance at a wall clock: a visible, persistent reference that doesn't require pulling out a phone or peeking at a tiny menu-bar widget. The difference is that a browser-based clock can be huge, theme-able, and one keystroke away from full screen.
Why use this online clock?
- Full-screen by design. One click hides every UI element except the time. Great for video calls where you want the time visible behind you, for cooking timers next to the stove, or for kids learning to tell the time.
- Seconds-precision display. Most clocks on a phone or laptop hide seconds. This one shows them by default — useful for any task where seconds matter (live broadcasts, exam timing, OBS overlays, sports referees).
- Any time zone. Set the clock to your local time, or pin it to another time zone — Tokyo, London, Los Angeles, UTC — and keep it open while you work with someone in that region.
- Themeable. Black-on-white for daytime focus, OLED-friendly black for night, gradient themes for streamers, or set a custom background image. Everything saves in your browser.
- Embeddable as a widget. If you run a website, you can paste our clock widget code into any page so your visitors see a live clock too.
Who is this online clock for?
The same big readable clock works in very different contexts. A few of the most common:
- Classrooms and schools — project the clock onto the front-of-room screen so every student can see the time during exams, timed reading, or class transitions.
- Remote teams and Zoom calls — keep the clock open in a side window so you can see the time without leaving your meeting view; switch the time zone to a colleague's local time when scheduling.
- Streamers and broadcasters — capture the clock as an OBS browser source for an on-screen timestamp during live streams.
- Kitchen and cooking — use it on a tablet propped on the counter so you can read the time across the room without unlocking your phone.
- Reception and lobby displays — full-screen clock on a TV or monitor, themed to match your brand.
- Personal focus tools — a clean, distraction-free clock as the only thing on a secondary monitor while you do deep work.
How accurate is a browser-based clock?
The clock you see here is read from your device's system clock — the same clock your OS shows in the menu bar or notification area. Modern operating systems keep that clock synchronized using Network Time Protocol (NTP), which traces back to atomic clocks at official time labs (NIST in the United States, NPL in the United Kingdom, PTB in Germany, and others). Once your OS has done its part, a browser-rendered clock is typically accurate to within a few hundred milliseconds of true atomic time.
For practical use cases — meetings, exams, classroom timing, kitchen cooking, OBS overlays — that's vastly more precision than is needed. If you suspect your clock is drifting, the fix is at the OS level (re-sync system time), not in the browser.
12-hour vs 24-hour format
The clock can display either format. 12-hour (with AM/PM) is standard in the United States, Canada, the Philippines, and a few other regions. 24-hour (also called "military time") is the international standard and is the default in most of Europe, Latin America, Asia, and Africa. Toggle between them in the settings panel — your choice is remembered.
Daylight Saving Time
The clock follows your device's time zone settings, which means it automatically jumps forward in spring and back in autumn for any region that observes Daylight Saving Time (DST). If you've set the clock to a specific city via the settings, that city's local DST rules apply — not your own. Cities that don't observe DST (most of Asia, most of Africa, Hawaii, Arizona, the equatorial zone) stay on the same offset year-round.
Major time zones at a glance
| Time zone | Offset (standard) | Where it's used |
|---|---|---|
| UTC | +00:00 | Reference for all other zones |
| GMT | +00:00 | United Kingdom (winter), West Africa |
| CET | +01:00 | Most of continental Europe |
| EST | −05:00 | US East Coast, parts of Canada |
| CST | −06:00 | US Central, Mexico City |
| PST | −08:00 | US West Coast, Vancouver |
| JST | +09:00 | Japan, Korea |
| IST | +05:30 | India, Sri Lanka |
A short history of clocks
The journey from sundials to the online clock you're reading is one of the most interesting strands in the history of measurement. Sundials (around 1500 BCE) measured the day by the position of a shadow. Water clocks (clepsydras) followed, then mechanical escapement clocks in medieval Europe — early ones drifted by 15 minutes a day. The pendulum clock (Christiaan Huygens, 1656) cut that to seconds per day. Quartz oscillators in the 1920s reached parts per million accuracy. Modern cesium atomic clocks are stable to better than one second in 100 million years.
A browser clock is at the very far end of that line: software running on a device that pulls its time from a network of atomic clocks, displayed on whatever screen happens to be in front of you. The same precision used to coordinate satellites and stock markets, in a tab.
Other clock and time tools on Time.now
Once you have the time, you often need to do something with it. A few related tools:
- World clock — see the time in dozens of cities at once.
- Time zone converter — convert between any two zones.
- Stopwatch — count up from zero, with lap times.
- Countdown timer — count down from a set duration.
- Alarm clock — browser-based alarm that fires at a set time.
- Calendar — month, year, and date utilities.
- Unix time — current Unix timestamp + converter.
Frequently Asked Questions
Is this online clock accurate?
Yes, within the limits of your device. The clock reads the system time of the device you're using, which most operating systems sync to NTP (Network Time Protocol) servers — the same source ultimately traceable to atomic clocks. Browser-rendered clocks are usually accurate to within a few hundred milliseconds. For most uses (meetings, exams, cooking, classroom display) that is far more precise than needed.
Does the clock work in full screen?
Yes. Click the Fullscreen button on the dock and the clock fills your entire monitor — perfect as a screensaver, classroom display, or kitchen wall clock. Press Esc to exit.
Can I show seconds, switch to 24-hour, or hide the date?
Yes. Open the settings panel (sliders icon) and toggle Show Seconds, 12-Hour Format, Show Date, and Show Location independently. Your preferences are saved in your browser.
Can I display a different time zone?
Yes. The location selector inside settings lets you pick any IANA time zone — for example, set the clock to Tokyo while you're in New York. Daylight Saving Time is handled automatically.
Will my customizations persist?
Yes. Theme, format, time zone, and toggle settings are saved in browser local storage. They'll be restored next time you open the page in the same browser.
Is the clock free to use? Can I embed it on my own site?
Does it work offline?
Once the page is loaded, the clock continues to tick from your device's internal time even if you lose internet. Reconnecting will not change the visible time unless your system clock has drifted.
Does this online clock work on mobile and tablet?
Yes. The interface is responsive and works in iOS Safari, Android Chrome, and on tablets. You can pin it to your home screen for one-tap access.