Examples
Examples
Try the starting example
- Required service labels joined by |
- API|Web
- Incidents: ID, service, starts, ends; fixed-offset YYYY-MM-DDTHH:MM; or none
- A,API,2026-10-20T09:00,2026-10-20T09:20 B,API,2026-10-20T09:10,2026-10-20T09:30 C,Web,2026-10-20T09:20,2026-10-20T09:50
- Observation starts, inclusive
- 2026-10-20T09:00
- Observation ends, exclusive
- 2026-10-20T10:00
- Observed service availability by time (%)
- API: 50; Web: 50
- Union downtime minutes by service
- API: 30; Web: 30
- Minutes at least one required service is down
- 50
- Minutes every required service is down
- 10
Try another scenario
- Required service labels joined by |
- API|Web
- Incidents: ID, service, starts, ends; fixed-offset YYYY-MM-DDTHH:MM; or none
- A,API,2026-10-20T09:00,2026-10-20T09:20 B,API,2026-10-20T09:10,2026-10-20T09:30 C,Web,2026-10-20T09:30,2026-10-20T10:00
- Observation starts, inclusive
- 2026-10-20T09:00
- Observation ends, exclusive
- 2026-10-20T10:00
- Observed service availability by time (%)
- API: 50; Web: 50
- Union downtime minutes by service
- API: 30; Web: 30
- Minutes at least one required service is down
- 60
- Minutes every required service is down
- 0
Calculation method
Calculation method
Observed service availability by time (%)
100×(1−union clipped service downtime/observation minutes).
Union downtime minutes by service
Clip incidents to the half-open observation window and union overlapping intervals separately per service.
Minutes at least one required service is down
Union incident intervals across all supplied services.
Minutes every required service is down
Integrate intervals where each required service has at least one active incident.
Symbols and units
- a
- Required service labels joined by |
- b
- Incidents: ID, service, starts, ends; fixed-offset YYYY-MM-DDTHH:MM; or none
- c
- Observation starts, inclusive
- d
- Observation ends, exclusive
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Assumptions & limits
Assumptions & limits
- A time-based incident-log worksheet, not a request-based SLI or proof of user impact. Missing incident records are treated as no recorded downtime; timestamps use one fixed-offset clock with half-open intervals.
Are these inputs private?
These calculations run in your browser. A shared link contains the values you choose to share. Only questions submitted to the separate AI finder are sent to OpenAI.
Further reading
NIST: combinatorial testing and coverage measurement; audit rules are explicitly supplied ↗
Background reading; this does not imply endorsement or independent review of SumFizz.