Service-Level Indicator (SLI)
Definition
An SLI measures a concrete property of service quality, such as availability or response time.
An SLI is a quantitatively measured property of a service, such as success rate, latency, or availability from the user’s perspective.
Simply explained
A measurement shows how well a service actually performs, for example how often requests succeed.
Why it matters in practice
The term contributes to secure, maintainable, and high-performance web applications as well as resilient technical decisions.
Example from business
An online shop measures the proportion of successful checkout requests below a defined latency.
Limits and pitfalls
- An easily measurable indicator is not automatically relevant to users; average latency can hide outliers.
Origin & history
Google’s SRE model popularized the clear separation between indicator, objective, and agreement.
Use in mid-sized companies
- Possible application: An online shop measures the proportion of successful checkout requests below a defined latency.
Frequently asked questions
What does Service Level Indicator (SLI) mean?
An SLI is a quantitatively measured property of a service, such as success rate, latency, or availability from the user’s perspective. What should be considered? An easily measurable indicator is not automatically relevant to users; average latency can hide outliers.
Sources
- Site Reliability Engineering, Service Level Objectives · Google, Site Reliability Engineering, Service Level Objectives
Source checked on 10.10.2026. Editorial application examples are hypothetical; no evidence of real customer results.
Editorially reviewed on: