Check a Macs Uptime and Reboot History

The “uptime” of a computer is how long it has been since it was last rebooted or started up. Since Macs are very stable and generally OS X users rarely have to reboot their machines, the uptime of Macs can reach impressive numbers. You can check the uptime and reboot history of any Mac if you want to find this information yourself, we’ll show you how.

Here’s how to check the uptime in days (or hours) and the rebooting history both via the Command Line of OS X, and also how to find ‘time since boot’ through the System Information profiler on a Mac.

How to Check a Macs Uptime

To check your Macs uptime, simply type ‘uptime’ in the Terminal. Terminal is an application found within /Applications/Utilities/ and is included in every version of Mac OS X.

uptime

Hit the return key and you’ll find the answer. The screen shot example shows a Mac with a 10 day uptime, but these numbers can easily reach into hundreds of days for some machines in some situations.

In the below example, uptime is reporting that we have a Mac that has been up for 21 hours and 40 minutes.

YourMac:~ user$ uptime
10:33 up 21:40, 4 users, load averages: 0.09 0.19 0.21

And another example on of uptime is reporting 24 days:

$ uptime
14:28 up 24 days, 22:06, 3 users, load averages: 3.41 4.21 4.08

The uptime will vary per machine, depending on how frequently it is rebooted, updated, shut down, and even crashed. Speaking of restarting a machine, you can also retrieve reboot history through the command line as well.

How to Check a Macs Reboot History

To check the reboot history of your Mac, type ‘last reboot’ in the Terminal. This will provide you with the dates and times of the last few reboots the machine has gone through.

YourMac:~user$ last reboot
reboot ~ Tue Sep 22 12:52
reboot ~ Sun Aug 30 23:17
reboot ~ Sat Aug 29 01:12
reboot ~ Fri Aug 28 22:07
wtmp begins Fri Aug 28 22:07

This can be extremely helpful when troubleshooting, or even just for finding out how often a Mac gets booted, and is a nice command to use in addition to uptime.

Find “Time Since Boot” from System Information

Outside of the command line, you can also retrieve uptime information from the more familiar GUI of Mac OS X:

1. Pull down the Apple menu and hold down the OPTION key, then select “System Information”
2. Click on “Software” on the side menu to see “System Software Overview”
3. Look for “Time since boot” to see the uptime in days, hours, and minutes

This method is easier though it own’t provide you with user information, load averages, or the reboot history.

Not to brag or anything, but I love the fact that that unless I have run Software Update, I rarely have to reboot my Mac at all, and while this might not be that exciting to most Mac users, for a relatively recent Windows convert I find this particularly nice. So naturally with my Mac geekiness I find it fun to check the uptime and reboot history of my Mac and others, it’s easy to do and it’s actually functionally useful too for troubleshooting certain Mac problems.

Updated on 5/16/2015, if you have an impressive uptime on your Mac, let us know in the comments.