SLA uptime calculator

The downtime budget is for the whole period, not per incident: 43.2 minutes a month could be one outage or forty-three, the math does not care. Error budget use is observed downtime divided by allowed downtime, the framing Google's SRE book uses. Maintenance is subtracted from the denominator before the target applies, which is a contract decision, not a law of nature; if your SLA does not exclude maintenance, leave that field at zero. Series composition assumes components fail independently, which real systems rarely do.