How to calculate annual uptime
Annual uptime = (525,600 minutes − downtime minutes) ÷ 525,600 × 100. Sum every incident across the year, including the “minor” ones. Twelve five-minute blips cost as much as one hour-long outage.
Annual figures smooth over bad months, which is why they flatter vendors: a service that was down an entire afternoon in March can still report 99.9% for the year. Track monthly numbers alongside the annual one to keep the story honest.
Downtime allowed at each SLA level
| Uptime | Per day | Per month | Per year |
|---|---|---|---|
| 99% Two nines | 14m 24s | 7h 12m | 3d 15h |
| 99.9% Three nines | 1m 26s | 43m 12s | 8h 45m 36s |
| 99.95% | 43s | 21m 36s | 4h 22m 48s |
| 99.99% Four nines | 9s | 4m 19s | 52m 34s |
| 99.999% Five nines | 864ms | 26s | 5m 15s |
| 99.9999% Six nines | 86ms | 3s | 32s |
| 99.9999999% Nine nines | 86μs | 2.6ms | 32ms |
SLA calculation cheatsheet
Availability calculation
Availability (%) = (Total Time - Downtime) / Total Time × 100Example: If a service was down for 7.3 hours in a 30-day month:
- Total Time = 30 days × 24 hours = 720 hours
- Availability = (720 - 7.3) / 720 × 100 = 98.99%
Response time SLA
Response Time Compliance (%) = (Responses Within Threshold / Total Responses) × 100Mean time metrics
- MTBF (Mean Time Between Failures) = Total Operational Time / Number of Failures
- MTTR (Mean Time To Repair) = Total Repair Time / Number of Repairs
- MTTA (Mean Time To Acknowledge) = Total Time to Acknowledge / Number of Incidents
Service credit calculation
Service Credit = (Monthly Service Fee) × (Credit Percentage for SLA Breach)SLA penalty example
- If availability drops below 99.9% but remains above 99.0%: 10% credit
- If availability drops below 99.0%: 25% credit
Track SLAs and downtime metrics at a glance
Hyperping reports on service reliability using data collected by your monitors. Select the reporting period, then review the results in the dashboard or export them.
- Track uptime, Mean Time to Recovery (MTTR), and SLA compliance for any reporting period.
- Export the selected period as a CSV file for audits, client reports, spreadsheets, or internal analysis.
- Review the complete incident history and use filters to narrow the records included in your report.
SLA & uptime management guides
What is uptime?
Uptime is the amount of time that a service is available and operational, typically expressed as a percentage over a given period such as a month or a year.
What is an SLA?
A service-level agreement (SLA) defines the level of service you expect from a vendor, laying out the metrics by which service is measured, as well as remedies or penalties should agreed-on service levels not be achieved.
How to prevent downtime?
Redundancy, monitoring and alerting are key to ensure a safe and reliable service.
Frequently asked questions
- How do you calculate availability?
- Availability (%) = (Total Time − Downtime) / Total Time × 100. For example, a service that was down 7.3 hours in a 30-day month (720 hours) has an availability of (720 − 7.3) / 720 × 100 = 98.99%.
- How much downtime does 99.95% uptime allow?
- At 99.95% uptime, the maximum allowed downtime is 43 seconds per day, 21 minutes 36 seconds per 30-day month, and 4 hours 22 minutes 48 seconds per 365-day year.
- What's the difference between 99.9% and 99.99% uptime?
- Each additional nine reduces allowed downtime tenfold: 99.9% allows about 8 hours 46 minutes of downtime per year, while 99.99% allows just under 53 minutes. Meeting 99.99% generally requires automated failover, since a human response rarely fits inside the budget.
- How do I track SLA compliance?
- Continuous uptime monitoring measures availability from outside your infrastructure and records every outage. Hyperping checks your endpoints at up to 30-second intervals from multiple regions and reports uptime, MTTR, and SLA compliance over any period.
- How do I calculate annual uptime from downtime?
- Subtract total downtime from the total measured time in the year, divide the result by the total measured time, and multiply by 100. Use the same definition of downtime throughout the year and document any excluded maintenance.