Error Budget

An error budget is the amount of unreliability you are allowed before breaching your SLO, the gap between your target and 100%.

If your SLO is 99.9% over 30 days, your error budget is 0.1%, about 43 minutes of downtime. As incidents consume that budget, the remainder tells you how much risk you can still take.

Error budgets turn reliability into a shared, data-driven decision: budget left means you can ship faster; budget spent means it is time to slow down and stabilise.