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SLA availability

Contracts may exclude maintenance or define other measurements. No compensation calculation.

Quick answer · example

How much downtime does a 99.9% SLA allow?

Over 30 days, 99.9% availability mathematically corresponds to 2592 seconds of downtime: 43 min 12 s. Contract terms determine exclusions and compensation.

Calculation assumptions

Contracts may exclude maintenance or define other measurements. No compensation calculation.

View the worked example ↓

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Result

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Formula and assumptions

seconds = (1−availability/100) × days × 86400

Contracts may exclude maintenance or define other measurements. No compensation calculation.

All amounts use the same currency of your choice. These are estimates, not measurements or offers.

How to use this calculator

Convert availability targets into mathematical downtime. Use the actual number of days. The tool does not monitor services or interpret contract exclusions and compensation.

Worked example

  1. At 99.9 %, the downtime fraction is 1 − 0.999 = 0.001.
  2. 30 days contains 30 × 24 × 3600 = 2,592,000 seconds.
  3. Multiplying by 0.001 gives 2592 seconds, or 43 min 12 s.

Example result

Time (seconds)
2,592

Interpreting the result

Compare targets over the same period and measurement method. Contractual SLAs and internal SLOs may use different criteria. A server response does not guarantee that a visitor can complete a purchase or task.

Frequently asked questions

Does 99.9 % prevent a long outage?

No. A proportion over a period does not itself limit each incident or predict its timing.

Do all months allow the same downtime?

No. At the same percentage, 31 days permits more seconds than 28 days.

Does the result establish compensation rights?

No. Those depend on the contract, exclusions and measurement evidence.

References and method

Google SRE — SLO · References and method