What does uptime mean?
Uptime means the amount of time during which a machine, computer system, service, or other operation remains working and available. It is especially common in technology and engineering, where reliability is measured by contrasting periods of operation with periods of failure or maintenance. A service with 99.9% uptime, for example, is unavailable for a small proportion of the time over a stated period. The word is also used figuratively for how long a person remains active in a profession or how long an organization or event continues without interruption. In this broader sense, uptime suggests continuity, stability, and sustained presence. The expression often appears in commitments and service-level agreements, where a high uptime figure reassures customers that a system will be available when needed. Although uptime is closely related to availability and reliability, it primarily emphasizes duration rather than the overall quality of performance.
nounThe period during which a machine, computer system, service, or other operation is working or available for use. By extension, it refers to the length of time during which an organization, activity, or person remains active and operational.
- The period during which a machine, computer system, network, or service is operational and available for use.
- The period during which an organization, activity, or person remains active, available, or in operation.
"With scheduled maintenance and redundant servers, the platform maintained 99.99% uptime throughout the year."
"The technicians restored full uptime within thirty minutes."
"Her long uptime in the industry gave her an unusually broad understanding of the profession."
The plural is grammatically possible but rarely needed, since uptime is normally treated as an uncountable noun.
"The company compares the uptimes of its data centers across different reporting periods."
A service can boast 99.99% uptime and still be unavailable for the one hour that matters most.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does uptime come from?
Uptime is a compound formed from the English word “up” and “time,” both of which have Old English origins. The word emerged in industrial and technical usage during the mid-20th century, when the operating time of equipment and machinery became important to describe. Its modern use expanded with computing, telecommunications, and the language of system reliability and service availability.
How uptime is actually used
Uptime is standard in computing, telecommunications, engineering, and business-continuity contexts. It is usually treated as an uncountable noun, although a plural form exists. The figurative sense, referring to a person's active career or an activity's operating period, is less common but established.