Error budget calculator
SLO target → allowed downtime over time window.
SLO target 99.900%
99.000% 99.999%
Allowed downtime
Per hour 3.6s
Per day 1m 26s
Per week 10m 4s
Per month (30d) 43m 12s
Per quarter (90d) 2h 9m
Per year (365d) 8h 45m
What is error budget?
Error budget = (100% - SLO target). It's the maximum acceptable unreliability over a time window. For 99.9% SLO, error budget = 0.1% = 43.2 minutes/month of allowed downtime.
Use error budget to prioritize: high budget remaining → ship features faster. Burning budget fast → focus on reliability.