Error Budget

An error budget is the amount of failure a service is permitted before it breaches its SLO. If an availability objective is 99.9% over 30 days, the error budget is the remaining 0.1% of allowed downtime or failed requests for that window. It reframes reliability as a resource to spend rather than a number to maximize.

Teams use the budget to balance velocity and stability:

• Budget remaining — there’s room to ship changes and take measured risks.
• Budget exhausted — slow down, prioritize reliability work, and protect the SLA.