Online Clock (Full Screen)
A big, clean clock for your screen: digital, analog or both, with seconds, the date, 12 or 24-hour time and a one-click full-screen mode that can keep your display awake.
Tip: press F or double-click the clock for full screen. Settings are saved in this browser.
How to use the Online Clock (Full Screen)
- Pick a style: Digital, Analog or Both, then choose 24h or 12h.
- Choose what to show: tick or untick Show seconds and Show date.
- Set the look: pick a display theme and digit style. The Dark display theme is good for night-time or dim rooms.
- Press Start full screen (or press F, or double-click the clock). Press Esc or the Exit button to leave.
- Tick Keep screen awake to stop your laptop, tablet or phone from dimming while the clock is visible.
Ways to use a full screen clock
- Classrooms and exams: project a large clock so everyone can see the time left.
- Presentations and live streams: keep track of time on a second monitor.
- Home office: turn an old tablet or spare monitor into a desk clock with the dark display theme.
- Kitchens, gyms and workshops: a big, clear clock readable from across the room.
- Remote teams: show a colleague's time zone next to your own on a second device.
12-hour and 24-hour time compared
| 24-hour | 12-hour | 24-hour | 12-hour |
|---|---|---|---|
| 00:00 | 12:00 AM (midnight) | 12:00 | 12:00 PM (noon) |
| 01:00 | 1:00 AM | 13:00 | 1:00 PM |
| 06:30 | 6:30 AM | 18:30 | 6:30 PM |
| 09:45 | 9:45 AM | 21:45 | 9:45 PM |
| 11:59 | 11:59 AM | 23:59 | 11:59 PM |
To convert from 24-hour to 12-hour time, subtract 12 from hours above 12 and add PM. Hour 00 becomes 12 AM and hour 12 stays 12 PM.
How the analog hands are positioned
The hands turn clockwise from 12 o'clock. The hour hand moves 30° per hour plus 0.5° per minute, the minute hand 6° per minute plus 0.1° per second, and the second hand 6° per second. At 3:30:00 the hour hand is at 3 × 30 + 30 × 0.5 = 105° and the minute hand at 30 × 6 = 180°, so the angle between them is 75°.
Frequently asked questions
How do I make the clock full screen?
Press the Start full screen button, press the F key or double-click the clock. Press Esc or the Exit button in the top corner to go back. On iPhones, where web pages cannot use true full screen, the clock fills the browser window instead.
How do I stop my screen from turning off?
Tick Keep screen awake. The tool uses the Screen Wake Lock API, supported by Chrome, Edge, Safari 16.4+ and most modern browsers, to keep the display on while the page is visible. The lock is released automatically when you switch tabs and is requested again when you come back.
Is the online clock accurate?
It shows your device's system time, which is normally synchronised with internet time servers and accurate to within a fraction of a second. The display is aligned to the start of each second so the seconds tick exactly.
Can I show the time for another city?
Yes. Choose a time zone from the Time zone list, for example Europe/London or Asia/Tokyo. Daylight saving time is handled automatically.
Does the clock work offline?
Once the page has loaded, the clock keeps running without an internet connection because everything runs in your browser.
Are my settings saved?
Yes. Style, hour format, theme, digits, time zone and the other options are stored in your browser and restored on your next visit.