What is Error Budget?

An error budget quantifies how much downtime or errors a service can tolerate. For example, a 99.9% availability SLO gives an error budget of 0.1%, translating to about 8.76 hours per year or 43.8 minutes per month. Teams can spend this budget on risky deployments, experiments, and new features. When the budget is depleted, the team shifts focus to reliability improvements. This framework turns the tension between development speed and stability into a data-driven conversation, removing subjective arguments about when to slow down or speed up releases.