How to Make the Mac Menu Bar Clock Blink (Flash Separators)

Buried in Clock Options is one of macOS's oldest surviving switches: Flash the time separators. Turn it on and the colon in the menu bar clock blinks — half a second visible, half a second gone — once every second, forever. It looks like a novelty. It's actually a genuinely useful heartbeat for your Mac, and it costs zero pixels of menu bar space.

Turn on the blinking colon

1. Open System Settings → Control Center.
2. Scroll to the bottom and click Clock Options.
3. Turn on Flash the time separators.

The colon starts blinking immediately. The setting lives in the same place on macOS 13 Ventura, 14 Sonoma, and 15 Sequoia, and turning the toggle back off stops the blink just as instantly — that's the whole undo.

One requirement: the clock's Style must be Digital. The analog face has no separators to flash, so the option is disabled while Analog is selected.

Why anyone wants a blinking clock

The trick predates OS X — classic Mac OS and plenty of VCRs blinked their colons — but the practical reason it survives is diagnosis. The clock is drawn by the system's UI layer, and the blink is a visible once-per-second proof that the layer is still updating. When your Mac locks up, the pointer often keeps moving (it's handled separately, at a lower level) — which makes a freeze weirdly hard to confirm. You sit there wiggling the mouse over a screen that might be thinking or might be gone. With flashing separators, one glance settles it: colon still blinking means the system is alive and something specific (an app, a disk operation) is stalling; colon frozen means the UI itself has stopped, and you're likely headed for a force-restart. It's a beachball detector that works before the beachball shows up.

Flashing vs showing seconds

The Display the time with seconds toggle in the same sheet gives you an even richer heartbeat — a counter that visibly ticks — but it widens the clock by three characters and some people find rolling digits in their peripheral vision distracting. The flashing colon conveys the same "still alive" signal with zero added width and far less motion. Run both if you like; they're independent toggles, and both apply only to the digital style. If the blinking bothers you after a day, you know where the switch is.

Using the heartbeat when things go wrong

The blink earns its keep the day your Mac stops responding. The escalation logic: if the colon is still blinking, the system is alive — reach for Opt+Cmd+Esc and force-quit the one app that's stuck, or open Activity Monitor and sort by CPU to find the process pegging a core. Your other work is fine; don't reboot it away. If the colon has stopped along with everything else, the window server itself is wedged; give it a full minute (some stalls recover), then hold the power button for the forced restart you were going to do anyway — now with evidence it was justified.

It's a crude instrument, but it converts the most anxious moment in computing — "is it thinking or is it dead?" — into a one-glance answer, using a feature that costs nothing and sits in the corner of your eye. Not bad for a checkbox most Mac users have never seen.

When the colon stops blinking

If the blink ever freezes along with the rest of your screen, don't reach for the power button first — see what to do when your Mac is frozen for the escalation path from force-quitting one app to a safe forced restart.