Table of Nines: Complete SLA Uptime & Downtime Reference Chart
The Table of Nines is the standard Site Reliability Engineering (SRE) reference chart showing the exact maximum allowable downtime for every standard SLA tier, ranging from 90% (One Nine) to 99.9999% (Six Nines).
The Complete SRE Table of Nines Reference Matrix
Understand how each additional "nine" reduces allowable downtime by an order of magnitude (10x).
| Availability Tier | SRE Classification | Daily Allowance | Weekly Allowance | Monthly Allowance | Yearly Allowance |
|---|---|---|---|---|---|
| 90.0% | 1 Nine | 2h 24m | 16h 48m | 3d 1h 48m | 36.5 Days |
| 95.0% | 1.5 Nines | 1h 12m | 8h 24m | 1d 12h 54m | 18.26 Days |
| 99.0% | 2 Nines | 14m 24s | 1h 40m | 7h 18m | 3.65 Days |
| 99.5% | 2.5 Nines | 7m 12s | 50m 24s | 3h 39m | 1.83 Days |
| 99.9%Current | 3 Nines | 1m 26s | 10m 5s | 43m 50s | 8h 46m |
| 99.95% | 3.5 Nines | 43.2s | 5m 2s | 21m 55s | 4h 23m |
| 99.99% | 4 Nines | 8.64s | 1m 0s | 4m 23s | 52m 36s |
| 99.995% | 4.5 Nines | 4.32s | 30.2s | 2m 11s | 26m 18s |
| 99.999% | 5 Nines | 0.86s | 6.05s | 26.3s | 5m 16s |
| 99.9999% | 6 Nines | 0.086s | 0.60s | 2.63s | 31.56s |
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Frequently Asked Questions (Table of Nines SLA Reference Sheet)
Clear answers to common SRE, contractual, and technical SLA calculation questions.
Frequently Asked Questions
The Table of Nines is a logarithmic comparison chart showing how the number of "nines" in an availability target (99%, 99.9%, 99.99%, 99.999%) drastically cuts the permissible downtime by a factor of 10 for each additional nine.
90% (One Nine) allows 36.5 days of downtime per year, whereas 99.9999% (Six Nines) allows only 31.5 seconds of downtime per year—a difference of over 100,000x higher reliability.
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