Binary Clock
About the Binary Clock Screensaver
A binary clock displays the current time using the binary number system instead of traditional decimal digits. Each column of dots represents one decimal digit of the time using Binary-Coded Decimal (BCD) notation — a format widely used in digital electronics and computer science.
This live binary clock screensaver updates every second and shows hours, minutes, and seconds as six columns of glowing dots. Lit dots (indigo) represent a 1 bit; unlit dots (grey) represent a 0 bit. Add the values of the lit dots in each column to read the digit.
Click Fullscreen to use it as a true screensaver — the clock fills your entire screen, making it perfect for monitor displays, desks, or coding ambiance.
How to Read a Binary Clock
The clock has six columns, each representing one digit of the time in HH:MM:SS format. Each column has four rows with bit values of 8, 4, 2, 1 from top to bottom.
- Look at one column — for example, the first column (H₁, the tens digit of the hour).
- Find the lit dots — indigo dots are ON (1); grey dots are OFF (0).
- Add the row values — if the row labelled 2 and the row labelled 1 are lit, the digit is 2 + 1 = 3.
- Repeat for each column — read H₁H₂ for hours, M₁M₂ for minutes, S₁S₂ for seconds.
- Combine the pairs — H₁=1 and H₂=4 means the hour is 14 (2 PM).
Common Use Cases
Screensaver & Ambient Display
Use fullscreen mode to turn any monitor into a stylish binary clock display. Great for office desks, server rooms, or developer workstations.
Learning Binary Numbers
Practice reading binary by watching the live clock. Since it updates every second, you get constant real-world examples to decode.
Computer Science Education
BCD clocks are a classic teaching tool for CS and electronics courses. Use this tool to demonstrate binary-coded decimal encoding to students.
Desk Decor & Geek Aesthetic
A binary clock on a second screen or tablet makes for a conversation-starting piece that shows off your knowledge of low-level computing.
Frequently Asked Questions
What is a binary clock?
A binary clock shows the current time using binary numbers instead of decimal digits. Each time digit (hours, minutes, seconds) is represented in binary using lit and unlit indicators. This clock uses BCD (Binary-Coded Decimal) format, where each decimal digit is encoded separately in binary.
How do I read this binary clock?
Each column has four rows with values 8, 4, 2, 1 (top to bottom). Add the values of lit (indigo) dots in a column to get that digit. The six columns represent the two digits of hours, minutes, and seconds respectively — just like a normal HH:MM:SS clock.
What does BCD mean in a binary clock?
BCD stands for Binary-Coded Decimal. Instead of converting the entire time to one large binary number, each decimal digit is independently encoded in 4 bits. This makes reading the clock easier since you only need to decode one digit at a time.
Can I use this as a fullscreen screensaver?
Yes. Click the yellow Fullscreen button at the top right of the clock. The display fills your entire screen and the dots scale up for easy viewing from a distance. Press Escape or click Exit to return to normal view.
How often does the binary clock update?
The clock updates every second, in sync with your device's system time. The dot transitions use a smooth 300ms animation so changes are easy to follow.
Is this clock accurate?
The binary clock reads directly from your browser's local system time, so it is as accurate as the clock on your device. It does not connect to an external time server.