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SLA & Error Budget
Turn an uptime target into the downtime it actually allows.
Why this exists
“99.9% uptime” sounds nearly perfect until you see it permits 8.8 hours of downtime a year. Turns an availability target into the concrete error budget used in on-call planning and contract reviews.
🔒 Runs in your browser — nothing is sent anywhere
99.9% availability allows
per day
1m 26s
per week
10m 4s
per month
43m 49s
per quarter
2h 11m 29s
per year
8h 45m 56s
Error budget
✅ 20m of 43m 49s used, 23m 49s left. (45.6%)
That is 99.9544% availability for the month.
Dependencies in series
Every dependency multiplies. This is the usual reason a system misses a target that each of its parts meets.
Combined: 99.8401% — 14h 1m 10s a year