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The permitted amount of unreliability, defined as 1 minus the SLO, governing release decisions.
DESCRIPTION
An error budget quantifies acceptable unreliability for a service over a period, derived from the SLO (1 − SLO). When a team exhausts its error budget, feature releases slow or stop to prioritize reliability. This aligns development velocity with user expectations and business risk tolerance. Error budgets guide change policies, incident response priorities, and reliability investments.
ALTERNATIVE DEFINITIONS
Google SRE Book
The error budget is 1 minus the SLO.
Provides the canonical quantitative definition linking SLO and budget.
Google Cloud
The error budget is 1 - SLO and represents the maximum amount of unreliability a service can experience over a compliance period.
Connects numeric budget to operational policy over time windows.
RELATED TERMS
Service Level Objective Service Level Indicator SLA Availability Reliability Change Management Incident Management Release Freeze Risk Appetite Postmortem
COMPETING TERMS
Change Freeze Policy Zero Defects
RELATIONS
- Broader: Budget
KNOWLEDGE AREAS
Observability & Telemetry Testing & Validation Software Engineering
TARGET AUDIENCE
DevOps Engineer IT Manager Chief Technology Officer Product Owner Scrum Master AI Product Manager
EXTERNAL SOURCES
- Wikipedia - Service-level objective
- Google SRE Workbook - Practical SLO and budget implementation
- Google SRE Book - Policies when budgets are exceeded
TOP QUESTIONS
Why are Error Budgets useful?
They balance innovation and reliability by making risk explicit and measurable, guiding when to ship features versus improve stability.
Category: Relevancy
How do you calculate an Error Budget?
Subtract the SLO from 1 over a defined period, e.g., 1 − 99.9% availability equals 0.1% allowable downtime.
Category: Requirements
What happens when the Error Budget is exhausted?
Teams typically pause launches, focus on reliability, and review change policies until the budget recovers.
Category: Management
What is a common mistake with Error Budgets?
Using budgets without well-defined, user-centric SLIs leads to poor alignment with actual user experience.
Category: Mistakes
How granular should Error Budgets be?
Service-level budgets are common, but critical user journeys may warrant finer segmentation.
Category: Opinion
Can Error Budgets apply to latency SLOs?
Yes, budgets can cover percentiles of latency, availability, correctness, or freshness based on SLIs.
Category: Example
How do Error Budgets impact release strategy?
They inform canarying, rollout pace, and rollback thresholds to control risk.
Category: Management
Who should own the Error Budget?
Service owners jointly with product management, ensuring business and engineering alignment.
Category: Requirements
How to start using Error Budgets?
Define user-centric SLIs/SLOs, compute budgets, and establish clear policies tied to budget consumption.
Category: Requirements