Check Mac uptime — and why it matters

“When did you last restart it?” is the oldest IT question for a reason — most weird Mac behaviour just dissolves after a fresh boot. Knowing your current uptime tells you whether you’ve earned a restart yet, and on a Mac you usually have, because most of us close the lid for weeks at a time without ever rebooting.

How to check uptime

uptime in Terminal

The Unix classic:

uptime

You’ll see something like 14:32 up 22 days, 18:11, 3 users, load averages: 1.32 1.45 1.28. That’s “22 days since the last boot.” On a Mac that’s been mostly asleep, it counts as uptime — sleep is not a reboot.

System Information

1. Hold Option, click the Apple menu, choose System Information.
2. In the sidebar, click Software.
3. Look for Time since boot.

Activity Monitor

There isn’t a direct uptime field, but you can infer it from the oldest still-running system process. Less useful than just running uptime.

A menu bar monitor

Beacon’s detail panel shows current uptime alongside other system stats — handy as a quick “should I restart?” check without launching anything.

1. Install Beacon.
2. Open the panel; uptime appears with the other system info.

When is too long?

Honestly, modern macOS is fine running for weeks. There’s no equivalent of the old Windows “you must reboot weekly” advice. That said, things drift:

• Memory creep — long-running apps accumulate fragmentation and minor leaks. A reboot resets the slate.
• Kernel extensions and helpers — some background daemons (third-party VPNs, drivers, sync agents) genuinely benefit from a fresh start.
• Pending system updates — security updates often want a reboot to finish applying. macOS will nag, but a 30-day-uptime Mac may still have pending updates queued.
• Locale, calendars, certificates — small things that get re-fetched at boot can be out of date after weeks.

A useful rule: reboot voluntarily once a month, or when something feels weird, or when you’re installing an update anyway. Less often than that is fine; more often is unnecessary.

What “uptime” actually counts

Worth knowing:

• macOS counts uptime from boot, not from last sleep. Closing the lid pauses everything but doesn’t reset the counter.
• A kernel panic counts as a reboot. If your uptime is “5 hours” but you haven’t restarted, check Console for panic logs.
• last reboot in Terminal shows every boot in recent history with timestamps — handy if you’re curious how often the machine is panicking or being shut down for updates.

Watching uptime climb is one of the small pleasures of a stable system. Three-week uptime on a daily-driver MacBook is genuinely a sign things are well.