Error Budget Calculator: Track SLO Burn Rate

An error budget is the maximum amount of unreliability your SLO allows within a given time window. If your SLO is 99.9%, your error budget is 0.1% of total requests (or time). Once the budget is exhausted, the team should prioritize reliability over new features.

Burn rate measures how fast you're consuming your error budget. A burn rate of 1x means you'll exhaust the budget exactly at the end of the window. 2x means you'll run out halfway through. Google SRE recommends alerting at 14.4x (2% budget in 1 hour) and 6x (5% budget in 6 hours).

The typical policy is to freeze feature releases and redirect engineering effort to reliability work — fixing bugs, adding redundancy, improving alerting — until the budget recovers in the next window or a new budget period begins.

SLI (Service Level Indicator) is a measurement — e.g. proportion of successful requests. SLO (Service Level Objective) is the internal target — e.g. 99.9% of requests succeed. SLA (Service Level Agreement) is the contractual promise to customers, usually with financial penalties.