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Binary Clock

Current time displayed in binary-coded decimal.

Show decimal labels
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H
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Bit values (top → bottom): 8 · 4 · 2 · 1

Binary Clock — Learn to Read Time in Binary

This binary clock shows the current time using binary-coded decimal (BCD) format. Each pair of columns represents hours, minutes, and seconds. Filled dots are 1; empty dots are 0. Toggle the decimal labels on to see the value of each column while you learn.

How to read a binary clock

Each column is read from bottom to top. The bottom dot has a value of 1, the next is 2, then 4, then 8. Add the values of all filled (lit) dots in a column to get the digit. Two columns side by side form one number — the left column is the tens digit and the right is the units digit.

For example, if the hours units column has the bottom two dots lit, that's 1 + 2 = 3. If the hours tens column has only the bottom dot lit, that's 1. Together, the time reads 13 hours — or 1:00 PM. Turn on the decimal labels above to see each column's value updated in real time as you practice.