Error Budget
The allowed amount of unreliability derived from SLOs. If your SLO is 99.9% uptime, your error budget is 0.1% (about 43 minutes/month). Once exhausted, freeze deployments.
What is Error Budget?
The allowed amount of unreliability derived from SLOs. If your SLO is 99.9% uptime, your error budget is 0.1% (about 43 minutes/month). Once exhausted, freeze deployments.
Error Budget is a advanced concept that sits in the Reliability & Resilience area of system design. Engineers reach for it whenever they need to reason about real-world trade-offs in that space — not just for textbook correctness, but because real production systems at companies like Netflix, Amazon, and Google make these decisions every day.
If you want to go deeper than this definition — with diagrams, code, and a quiz to lock it in — work through the "Error Budget" lesson linked below. It walks through the why, the mechanism, the trade-offs, and how the giants actually use it in production.
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See also
Related glossary terms you might want to look up next.
SLO
Service Level Objective: a target value for an SLI, like '99.9% of requests under 300ms.' The internal engineering goal that drives reliability investment.
SLI
Service Level Indicator: a quantitative measure of service behavior, like the proportion of requests faster than 300ms. The raw metric that feeds SLOs.
SLA
Service Level Agreement: a contractual commitment between provider and customer specifying uptime, response time, and penalties for breaches. The business version of an SLO.