Uptime SLOs and SLAs: Setting Targets That Work
Picking the right uptime targets is a balance between customer expectations, engineering effort, and the reality of distributed systems. This guide explains how to set SLOs and SLAs that are credible and useful.
Start with customer impact
Define what being offline means for your users. Is it a full outage, partial degradation, or latency above a threshold? Clear definitions help your team measure reliability consistently.
SLOs vs SLAs
Service Level Objectives are internal reliability targets. Service Level Agreements are customer-facing commitments that often include penalties. Set SLOs higher than your SLA so you can meet the promise even when incidents happen.
Pick a timeframe and error budget
Most teams track uptime monthly or quarterly. The error budget is the amount of downtime you can tolerate while still meeting the SLO. When the budget is exhausted, slow new releases and focus on stability.
- 99.9% monthly uptime allows about 43 minutes of downtime.
- 99.95% monthly uptime allows about 22 minutes of downtime.
- 99.99% monthly uptime allows about 4 minutes of downtime.
Align alerts with objectives
Tie alert thresholds to what would burn your error budget, not every minor blip. This keeps your team focused on incidents that matter.
Share reliability transparently
Use uptime reports and status pages to communicate reliability trends with customers and internal teams. Transparent reporting builds trust even when issues occur.