Millisecond Clock
Real-time high-precision digital clock displaying hours, minutes, seconds, and milliseconds with fullscreen mode and customizable appearance
Readme
How accurate is your computer clock?
Most digital clocks update once per second, but the time between those ticks is invisible. A millisecond is one thousandth of a second — far too fast for humans to perceive individually, yet critically important in fields like software development, network diagnostics, scientific experiments, and competitive gaming. Standard clocks round to the nearest second, hiding the sub-second precision that modern computers are fully capable of displaying.
Precise timekeeping matters when you need to synchronize events, measure short durations, or simply verify that your system clock is running correctly. Seeing milliseconds tick in real time gives you an immediate, intuitive sense of how fast a thousandth of a second actually passes.
Tool description
This millisecond clock displays the current time from your device with millisecond-level precision, updating in real time using the browser's animation frame loop. It supports both 12-hour and 24-hour formats, optional date display, and a fullscreen mode that turns your entire screen into a large, distraction-free clock. Colors, font, and size are all customizable.
Features
- Real-time millisecond precision — updates every animation frame for smooth, accurate millisecond display
- Fullscreen mode — expand the clock to fill your entire screen, ideal for presentations or wall displays
- 12-hour and 24-hour formats — switch between AM/PM and military time instantly
- Fully customizable appearance — adjust font family, font size (40–300px), text color, and background color
- Toggle individual elements — show or hide the date, seconds, milliseconds, and blinking separator independently
Options explained
| Option | Description |
|---|---|
| Time Format | Switch between 24-hour (default) and 12-hour (AM/PM) display |
| Font Family | Choose from Monospace, Courier New, Segoe UI, System UI, Georgia, or Arial |
| Font Size | Adjust the clock digits from 40px to 300px using a slider |
| Text Color | Pick any color for the time digits and date text |
| Background Color | Pick any color for the clock background area |
| Show Date | Toggle the full date line (weekday, month, day, year) below the clock |
| Show Seconds | Toggle the seconds portion of the time display |
| Show Milliseconds | Toggle the millisecond counter after the seconds |
| Blinking Separator | Make the colon separators blink on and off every half second |
| Fullscreen | Expand the clock to fill your entire screen; press ESC to exit |
Use cases
- Developers and engineers debugging time-sensitive code who need to visually confirm system clock precision and see exact timestamps in real time
- Presentations and events where a large, readable clock on screen helps keep speakers and participants on schedule
- Network and latency testing where observing millisecond-level time changes helps correlate logs and packet captures with the current system time
How it works
The clock uses the browser's requestAnimationFrame loop to read Date and render the current time on every frame (typically 60 times per second). This produces smooth, flicker-free updates and ensures the millisecond counter reflects the actual system time as closely as the browser allows. Colors automatically adapt to your system's light or dark theme unless you customize them manually.
Tips
- Use a monospace font for the most stable layout — proportional fonts cause digits to shift as values change
- In fullscreen mode, the cursor automatically hides for a cleaner display
- The clock reads your device's local time — make sure your system clock is synchronized (via NTP) if you need accurate absolute time
- Combine hidden seconds + visible milliseconds for an unusual stopwatch-style display
FAQ
Does this tool send my time data anywhere? No. Everything runs locally in your browser. No data is transmitted.
Why do the milliseconds sometimes appear to skip numbers? The browser renders frames at approximately 60 fps (~16ms intervals), so not every millisecond value will be displayed. This is normal and does not affect accuracy.
Can I use this as a screensaver or ambient display? Yes. Enter fullscreen mode, choose your preferred colors, and leave the tab active. The cursor hides automatically in fullscreen.