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Binary Clock Online — Free Real-Time BCD Binary Clock

A Real Binary Clock, Not a Gimmick Font

Time shown as actual binary — each decimal digit of the hour, minute, and second drawn as its own column of lit and unlit dots, the same BCD (binary-coded decimal) convention hardware binary clocks use, running as a page instead of a soldered kit.

Where People Put It

Developer desk display

A column of dots reads as background decoration to anyone glancing over, but tells the exact time to anyone willing to do the arithmetic — a quiet flex for a dev desk or homelab shelf.

A party trick or conversation starter

Pull it up on a shared screen and challenge someone to read the time off it cold — most people need a minute the first try, then can't stop doing it in their head afterward.

Practicing binary without flashcards

Glancing at real time values a few times a day builds the 8-4-2-1 habit faster than isolated drills, since there's an answer you already know to check yourself against.

Server room or homelab ambient display

Sits well next to blinking network gear and rack lights — it already looks like it belongs among status LEDs, unlike a conventional clock face.

How to Use

Four steps between you and a working set of blinking lights.

Open in any browser

The dots are already lit the moment the page loads — no app, no extension, and the layout holds up identically on a monitor, a tablet, or a phone propped on a desk.

Pick your dot color

Settings has all eight dot colors behind a single tap, saved locally so your pick is still there whenever you come back.

Tweak the display

The 12/24-hour toggle, seconds, and the date live as three independent switches — flipping one leaves the dot columns you're not looking at untouched.

Go fullscreen

Fullscreen strips the browser away entirely, leaving just the dot columns on screen; pair it with Keep Screen On if it's sitting on a shelf unattended.

Features

Everything the binary clock actually does.

12 / 24-hour format

Switching formats only changes how the digits are grouped — the underlying bit columns work exactly the same either way.

8 dot colors

Eight lit-dot colors to pick from in Settings, from a cool cyan to a warm amber, each rendered on the same dark background.

Fullscreen mode

One tap hides every browser control, leaving nothing on screen but the dot grid itself.

Keep screen on

The same Wake Lock mechanism used elsewhere on this site holds the tab awake here too — worth flipping on if the display is going to sit somewhere unattended.

Works everywhere

Resize the browser window or pull it up on a phone — there's no fine detail in a dot grid to lose, so it stays legible shrunk down or blown up.

Runs in your browser

Nothing here needs a login or a network call once the page has loaded — every dot is drawn locally, and your preferences stay put on this device.

FAQ

Starting with the question everyone actually has.

How do I read a binary clock?

Each column is one decimal digit, read top to bottom as 8-4-2-1 — add up the values next to the lit dots and you get that digit. Six columns in a row spell out hours, minutes, and seconds.

Why BCD instead of one long binary number?

A single binary number for the whole time would need a different number of digits depending on the hour, which shifts the whole layout throughout the day. BCD keeps each decimal digit in its own fixed column instead.

Is this the same as an actual binary clock kit?

Same underlying idea — BCD, lit versus unlit — but this one is a webpage instead of a soldered circuit board. No wiring, no case to build, just open the tab.

Does this show the date as well as the time?

Yes — toggle it on in Settings alongside seconds, independent of everything else on the display.

Will it keep my screen from sleeping?

It's off by default — switch it on in Settings if this is going to sit unattended on a shelf or rack, otherwise your device's own sleep timer stays in charge.

Does it work well next to other desk gear?

The glow colors pair naturally with RGB keyboards, case lighting, or a homelab rack — Green and Amber lean toward a classic terminal look, the rest lean brighter and more decorative.

From the Blog

Prefer a mechanical flip-card, retro pixel-grid, or neon gradient look instead? See the Flip Clock Online, Pixel Clock Online, or Neon Clock Online, or open the full Digital Clock to flip between every theme and setting.