A binary clock is a classic way to practice reading binary — and a genuinely fun visual once you get the hang of it. Instead of numerals, each decimal digit of the current time is shown as a column of lit and unlit dots.
What Is the Binary Clock?
The tool reads your device’s current time every second and renders it as a Binary-Coded Decimal (BCD) display — each of the six decimal digits in HH:MM:SS gets its own column of dots, with the dot values (1, 2, 4, 8 from bottom to top) adding up to that digit’s decimal value.
How to Use It
- Open the tool at /tools/binary-clock.
- Watch the dot columns update live, once per second.
- Toggle 12-hour or 24-hour format with the checkbox.
- To read a column: add up the values of the lit dots from bottom to top.
Key Features
- Live-updating BCD display, refreshed every second directly from your device’s system clock.
- Readable time label underneath the dots, so you can double-check your reading.
- 12-hour and 24-hour format toggle.
- Purely visual and educational — no data ever leaves your browser.
When to Use This Tool
- Learning or teaching binary numbers with a genuinely useful, real-time example.
- A fun, unconventional desk clock for a dev workspace.
- Practicing quick binary-to-decimal conversion casually throughout the day.
Try It Now
Open Binary Clock directly, or press ⌘K and type the tool name from anywhere on the site.
Part of the Productivity collection on WebdevToolbox — free, browser-based developer tools with no login required.