Uptime is a
measure of system reliability, expressed as the period of
time
Time is the continuous progression of existence that occurs in an apparently irreversible process, irreversible succession from the past, through the present, and into the future. It is a component quantity of various measurements used to sequ ...
a
machine
A machine is a physical system that uses power to apply forces and control movement to perform an action. The term is commonly applied to artificial devices, such as those employing engines or motors, but also to natural biological macromol ...
, typically a
computer
A computer is a machine that can be Computer programming, programmed to automatically Execution (computing), carry out sequences of arithmetic or logical operations (''computation''). Modern digital electronic computers can perform generic set ...
, has been continuously working and available. Uptime is the opposite of
downtime
In computing and telecommunications, downtime (also (system) outage or (system) drought colloquially) is a period when a system is unavailable. The unavailability is the proportion of a time-span that a system is unavailable or offline.
This is ...
.

It is often used as a measure of computer
operating system
An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs.
Time-sharing operating systems scheduler (computing), schedule tasks for ...
reliability or stability, in that this time represents the time a computer can be left unattended without
crashing or needing to be
rebooted for administrative or maintenance purposes.
Conversely, long uptime may indicate negligence, because some critical updates can require reboots on some platforms.
Records
In 2005,
Novell
Novell, Inc. () was an American software and services company headquartered in Provo, Utah, that existed from 1980 until 2014. Its most significant product was the multi-platform network operating system known as NetWare. Novell technolog ...
reported a server with a 6-year uptime. This level of uptime is common when servers are maintained under an industrial context and host critical applications such as banking systems.
Netcraft
Netcraft is an Internet services company based in London, England. The company provides cybercrime disruption services across a range of industries.
History
Netcraft was founded by Mike Prettejohn in Bath, Somerset. The company provides web s ...
maintains the uptime records for many thousands of
web hosting
A web hosting service is a type of Internet hosting service that hosts websites for clients, i.e. it offers the facilities required for them to create and maintain a site and makes it accessible on the World Wide Web. Companies providing web ho ...
computers.
A server running Novell
NetWare
NetWare is a discontinued computer network operating system developed by Novell, Inc. It initially used cooperative multitasking to run various services on a personal computer, using the IPX network protocol. The final update release was ver ...
has been reported to have been shut down after 16 years of uptime due to a failing hard disk.
A
Cisco
Cisco Systems, Inc. (using the trademark Cisco) is an American multinational digital communications technology conglomerate corporation headquartered in San Jose, California. Cisco develops, manufactures, and sells networking hardware, s ...
router had been reported to have been running continuously for 21 years as of 2018. As of April 11, 2023, the uptime had increased to 26 years, 25 weeks, 1 day, 1 hour, and 8 minutes until the router was later decommissioned and the final report of the uptime was 26 years, 28 weeks, 2 days, and 6 minutes.
Determining system uptime
Microsoft Windows
Windows Task Manager
Some versions of
Microsoft Windows
Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...
include an uptime field in
Windows Task Manager
Task Manager, previously known as Windows Task Manager, is a task manager, system monitor, and startup manager included with Microsoft Windows systems. It provides information about computer performance and running software, including names of ...
, under the "Performance" tab. The format is D:HH:MM:SS (days, hours, minutes, seconds).
systeminfo
The output of the
systeminfo
command includes a "System Up Time" or "System Boot Time" field.
C:\>systeminfo , findstr "Time:"
System Up Time: 0 days, 8 hours, 7 minutes, 19 seconds
The exact text and format are dependent on the language and locale. The time given by
systeminfo
is not reliable. It does not take into account time spent in
sleep
Sleep is a state of reduced mental and physical activity in which consciousness is altered and certain Sensory nervous system, sensory activity is inhibited. During sleep, there is a marked decrease in muscle activity and interactions with th ...
or
hibernation
Hibernation is a state of minimal activity and metabolic reduction entered by some animal species. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It is mos ...
. Thus, the boot time will drift forward every time the computer sleeps or hibernates.
NET command
The
NET
command with its
STATISTICS
sub-command provides the date and time the computer started, for both the
NET STATISTICS WORKSTATION
and
NET STATISTICS SERVER
variants. The command
NET STATS SRV
is shorthand for
NET STATISTICS SERVER
. The exact text and date format is dependent on the configured language and locale.
C:\>NET STATISTICS WORKSTATION , findstr "since"
Statistics since 8/31/2009 8:52:29 PM
Windows Management Instrumentation (WMI)
Uptime can be determined via
Windows Management Instrumentation
Windows Management Instrumentation (WMI) is a set of extensions to the Windows Driver Model that provides an operating system interface through which instrumented components provide information and notification. WMI is Microsoft's implementatio ...
(WMI), by querying the
LastBootUpTime
property of the
Win32_OperatingSystem
class. At the
command prompt
A command-line interface (CLI) is a means of interacting with software via commands each formatted as a line of text. Command-line interfaces emerged in the mid-1960s, on computer terminals, as an interactive and more user-friendly alternativ ...
, this can be done using the
wmic
command:
C:\>wmic os get lastbootuptime
LastBootUpTime
20110508161751.822066+060
The timestamp uses the format
yyyymmddhhmmss.nnn
, so in the above example, the computer last booted up on 8 May 2011 at 16:17:51.822. The text "LastBootUpTime" and the timestamp format do not vary with language or locale. WMI can also be queried using a variety of
application programming interface
An application programming interface (API) is a connection between computers or between computer programs. It is a type of software Interface (computing), interface, offering a service to other pieces of software. A document or standard that des ...
s, including
VBScript
VBScript (Microsoft Visual Basic Scripting Edition) is a deprecated programming language for scripting on Microsoft Windows using Component Object Model (COM), based on classic Visual Basic and Active Scripting. It was popular with system admi ...
or
PowerShell
PowerShell is a shell program developed by Microsoft for task automation and configuration management. As is typical for a shell, it provides a command-line interpreter for interactive use and a script interpreter for automation via a langu ...
.
Uptime.exe
Microsoft formerly provided a downloadable utility called
Uptime.exe
, which reports elapsed time in days, hours, minutes, and seconds.
C:\>Uptime
SYSTEMNAME has been up for: 2 day(s), 4 hour(s), 24 minute(s), 47 second(s)
The time given by
Uptime.exe
is not reliable. It does not take into account time spent in
sleep
Sleep is a state of reduced mental and physical activity in which consciousness is altered and certain Sensory nervous system, sensory activity is inhibited. During sleep, there is a marked decrease in muscle activity and interactions with th ...
or
hibernation
Hibernation is a state of minimal activity and metabolic reduction entered by some animal species. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It is mos ...
. Thus, the boot time will drift forward every time the computer sleeps or hibernates.
FreeDOS
The
uptime
command is also available for
FreeDOS
FreeDOS (formerly PD-DOS) is a free software operating system for IBM PC compatible computers. It intends to provide a complete MS-DOS-compatible environment for running Legacy system, legacy software and supporting embedded systems. FreeDOS ca ...
. The version was developed by M. Aitchison.
Linux
Using uptime
Users of
Linux
Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, pac ...
systems can use the BSD uptime utility, which also displays the system load averages for the past 1, 5, and 15-minute intervals:
$ uptime
18:17:07 up 68 days, 3:57, 6 users, load average: 0.16, 0.07, 0.06
Using /proc/uptime
Shows how long the system has been on since it was last restarted:
$ cat /proc/uptime
350735.47 234388.90
The first number is the total number of seconds the system has been up. The second number is how much of that time the machine has spent idle, in seconds. On multi-core systems (and some Linux versions) the second number is the sum of the idle time accumulated by each CPU.
BSD
Using uptime
BSD
The Berkeley Software Distribution (BSD), also known as Berkeley Unix or BSD Unix, is a discontinued Unix operating system developed and distributed by the Computer Systems Research Group (CSRG) at the University of California, Berkeley, beginni ...
-based operating systems such as
FreeBSD
FreeBSD is a free-software Unix-like operating system descended from the Berkeley Software Distribution (BSD). The first version was released in 1993 developed from 386BSD, one of the first fully functional and free Unix clones on affordable ...
,
Mac OS X
macOS, previously OS X and originally Mac OS X, is a Unix, Unix-based operating system developed and marketed by Apple Inc., Apple since 2001. It is the current operating system for Apple's Mac (computer), Mac computers. With ...
, and
SySVr4 have the ''uptime'' command (See ).
$ uptime
3:01AM up 69 days, 7:53, 0 users, load averages: 0.08, 0.07, 0.05
The uptime program on BSD is a
hard link
In computing, a hard link is a directory entry (in a Directory (computing), directory-based file system) that associates a name with a Computer file, file. Thus, each file must have at least one hard link. Creating additional hard links for a fil ...
to the w program. The w program is based on the
RSTS/E
RSTS () is a multi-user time-sharing operating system developed by Digital Equipment Corporation (DEC, now part of Hewlett-Packard) for the PDP-11 series of 16-bit minicomputers. The first version of RSTS (RSTS-11, #Versions, Version 1) was implem ...
,
TOPS-10
TOPS-10 System (Timesharing / Total Operating System-10) is a discontinued operating system from Digital Equipment Corporation (DEC) for the PDP-10 (or DECsystem-10) mainframe computer family. Launched in 1967, TOPS-10 evolved from the earlier "Mo ...
, and
TOPS-20
The TOPS-20 operating system by Digital Equipment Corporation (DEC) is a proprietary OS used on some of DEC's 36-bit mainframe computers. The Hardware Reference Manual was described as for "DECsystem-10/DECSYSTEM-20 Processor" (meaning the DEC PDP ...
SYSTAT program.
Using sysctl
There is also a method of using ''sysctl'' to call the system's last boot time:
$ sysctl kern.boottime
kern.boottime: Thu Apr 22 12:14:46 2010
OpenVMS
On
OpenVMS
OpenVMS, often referred to as just VMS, is a multi-user, multiprocessing and virtual memory-based operating system. It is designed to support time-sharing, batch processing, transaction processing and workstation applications. Customers using Op ...
systems, the
show system
command can be used at the
DCL command prompt to obtain the system uptime. The first line of the resulting display includes the system's uptime, displayed as days followed by hours:minutes:seconds. In the following example, the command qualifier
/noprocess
suppresses the display of per-process detail lines of information.
$ show system/noprocess
OpenVMS V7.3-2 on node JACK 29-JAN-2008 16:32:04.67 Uptime 894 22:28:52
The command output above shows that node JACK on 29 January 2008 at 16:32:04.67 has an uptime of 894 days 22 hours 28 minutes and 52 seconds.
See also
*
Availability
In reliability engineering, the term availability has the following meanings:
* The degree to which a system, subsystem or equipment is in a specified operable and committable state at the start of a mission, when the mission is called for at ...
*
List of POSIX commands
*
Maintenance window
*
System profiler
{{noref, date=September 2018
A system profiler is a program that can provide detailed information about the software installed and hardware attached to a computer. Typically workstations and personal computers have had system profilers as a common ...
* – can allow remote estimation of uptime
*
Website monitoring
Website monitoring is the process of testing and verifying that end-users can interact with a website or web application as expected. Website monitoring are often used by businesses to ensure website uptime, performance, and functionality is as ex ...
*
Who (Unix) – can display the time the system was booted
References
{{Windows commands
Real-time computing
Unix user management and support-related utilities
Fault-tolerant computer systems
Windows administration