How to check how long your Mac has been on

The quickest way to see how long your Mac has been on is to open Terminal and type uptime. It prints a single line, and the part after the word "up" is the time since the Mac last started. If it says up 12 days, 3:41, your Mac has not restarted in twelve days, three hours and forty-one minutes.

That number surprises a lot of people. Closing the lid or letting the Mac sleep does not reset it, so a MacBook that feels like it gets switched off every evening may have been running for weeks. Below: how to read the output, where else the same number shows up, what a normal uptime looks like, and when a restart is actually worth it.

Check uptime in Terminal

1. Open Terminal. It lives in Applications > Utilities, or press Command and Space and type Terminal.
2. Type uptime and press Return.
3. You get one line back, something like this:

16:52 up 3 days, 19:11, 4 users, load averages: 2.10 1.85 1.60

What each part means

• 16:52 is the current time.
• up 3 days, 19:11 is the uptime: three days, nineteen hours and eleven minutes since the Mac started. Shorter uptimes are written a little differently, such as up 2 mins or up 5:30 for five and a half hours.
• 4 users is the number of open login sessions, not the number of people. Your normal login counts as one, and so does every Terminal window or tab, so a Mac with one owner often shows several.
• load averages are three numbers that give a rough idea of how much work was waiting for the processor, averaged over the last 1, 5 and 15 minutes. You can ignore them for this question. If the Mac feels slow, Activity Monitor is a better place to find out why.

See when it last started

uptime tells you how long. If you want the date and time instead, type who -b, which prints a line like system boot 14 Oct 08:12. Typing last reboot lists recent restarts, newest first. That is handy when you want to know whether the Mac restarted itself overnight to finish an update.

Where else it shows, without Terminal

If you would rather not type commands, System Information has the same number.

1. Hold down Option and click the Apple menu.
2. Choose System Information.
3. Click the Software heading in the sidebar.
4. Look for Time since boot, which reads something like "3 days, 19 hours, 11 minutes".

You can also reach System Information through Apple menu > About This Mac. In recent versions of macOS that opens a short summary with a More Info button, and the System Report button at the bottom of the next window opens the same app.

Why the number is bigger than you expect

Uptime counts from the last time the Mac actually started up. Very few everyday actions do that.

These reset it:

• Choosing Restart or Shut Down from the Apple menu.
• Installing a macOS update, which usually restarts the Mac.
• A crash that makes the Mac restart on its own.
• A desktop Mac losing power, for example in a power cut.

These do not:

• Closing the lid of a MacBook.
• Sleep, including the Mac going to sleep by itself when you walk away.
• Locking the screen or turning off the display.
• Logging out and logging back in.
• Quitting every app.

The count also includes the time the Mac spent asleep. So a MacBook that is used for a few hours a day and sleeps the rest still adds a full day of uptime every day. That is why "I turn it off every night" so often turns out to mean "I close the lid every night".

What a normal uptime looks like

There is no number at which a Mac stops working. macOS is built to run for long stretches, and a long uptime on its own is not a fault. As a rough guide:

The longer a Mac runs, the more chances something has to drift. An app slowly holds on to more memory than it needs, a background process gets stuck, Bluetooth or Wi-Fi gets into a muddle, or an update sits downloaded but not installed because it needs a restart. None of this is guaranteed, and plenty of Macs run for a month without trouble. But a restart clears all of it in a minute or two, which is why many people settle on a weekly restart as a sensible default. There is more on that rhythm in how often you should restart your Mac.

When a restart is worth it

Look at the uptime, then look at how the Mac is behaving. A restart is usually worth it when:

• The Mac feels slower than it did a few days ago, with no obvious reason.
• An app keeps hanging or showing the spinning wait cursor, even after you quit and reopen it.
• Wi-Fi, Bluetooth, sound or a USB device stops working properly.
• Software Update says an update is ready and needs a restart.
• Activity Monitor's Memory tab shows the Memory Pressure graph sitting in yellow or red while you are not doing much.

Restart properly

1. Save your work and quit anything that holds unsaved changes.
2. Choose Apple menu > Restart.
3. If one app has been the trouble, untick "Reopen windows when logging back in" so it doesn't come straight back in the same state.

Restart and Shut Down both reset the uptime, so pick whichever suits you. Restart is quicker if you plan to keep working. Holding down the power button is for a Mac that has frozen completely, not for everyday use, because anything unsaved is lost.

Let something else keep count

Checking uptime is easy once you know the command. Remembering to check is the hard part, and it is the kind of chore Notchpals gives to its Tech care area. Gumdrop and Juice both cover it, and whichever one you have in your crew watches the same figure uptime prints. Once it passes a week, the character peeks out of the notch between 9 AM and 6 PM to suggest a restart, never more than once a week.

GumdropMy gears get sticky after a week. Yours too? Restart when you can.

Done tells it you have restarted. Later means one more try 20 minutes on, and only if the Mac still hasn't restarted by then. The uptime figure never leaves your Mac, and the restart itself is always your call.

The same characters also speak up when the battery runs low or the startup disk is nearly full, so one crew member covers three bits of Mac care that are easy to forget. If storage is your problem right now, see clearing space on a full startup disk. And if you would rather fold all of this into one habit, a weekly Mac care routine covers the restart, updates and storage in about five minutes.