Uptime / Availability Calculator
Calculate availability metrics and allowed downtime.
Availability Quick Reference
| Nines | Availability | Downtime/Year |
|---|---|---|
| 2 nines | 99% | 3.65 days |
| 3 nines | 99.9% | 8.76 hours |
| 4 nines | 99.99% | 52.6 minutes |
| 5 nines | 99.999% | 5.26 minutes |
| 6 nines | 99.9999% | 31.5 seconds |
Understanding Availability
Availability Formula
Availability = Uptime / (Uptime + Downtime)
Nines = -log₁₀(1 - Availability)
Nines = -log₁₀(1 - Availability)
Achieving High Availability
- Redundancy: N+1 or 2N configurations
- Geographic distribution: Multiple sites
- Automated failover: Fast detection and recovery
- Maintenance windows: Planned vs unplanned
- Monitoring: 24/7 NOC operations