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SLA calculator

Your SLA target, in allowed minutes.

An SLA percentage is hard to reason about on its own. This calculator converts any availability target into the actual downtime it allows per year, month, week, and day.

SLA calculator SLA uptime calculator availability percentage calculator nines table allowed downtime calculator
Calculate allowed downtime See the nines table
Scroll for the nines table

InputSLA model

Allowed downtime Error budget

Per year

0h

The month, week, and day figures below scale from this SLA target.

0h Per month
0h Per week
0h Per day
Reference

The standard nines table.

These are the commonly cited availability tiers and the downtime they allow per year, based on a 365-day, 8,760-hour year — the same year-length assumption used throughout this site.

Availability Common name Downtime per year
90% "one nine" 36.5 days
95% — 18.25 days
99% "two nines" 3.65 days
99.5% — 1.83 days
99.9% "three nines" 8.76 hours
99.95% — 4.38 hours
99.99% "four nines" 52.6 minutes
99.999% "five nines" 5.26 minutes
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FAQ

SLA calculator, answered.

Questions that come up when translating an SLA percentage into a real number.

How is allowed downtime calculated from an SLA percentage? Allowed downtime equals the total time in the period multiplied by the unavailable percentage (100 minus the SLA target). For a year, that is 8,760 hours multiplied by that fraction.
Why do the same SLA percentages appear on Wikipedia and vendor sites? The nines table is standard math, not a proprietary benchmark — anyone calculating unavailable time from an SLA percentage over a 365-day year arrives at the same figures.
What SLA target should I choose? That depends on your architecture and cost tolerance, not just ambition — each additional nine typically costs significantly more in redundancy and operational rigor than the one before it.
How does this relate to SLA credits? This calculator shows the budget; the SLA credits calculator shows what you owe a customer when you miss it. For the revenue impact of missing it, see the cost of downtime calculator.
Next step

Know your budget. Now price a breach.

Once you know how much downtime your SLA allows, use the SLA credits calculator to see what a breach actually costs in contract terms.

SLA credits calculator Cost of downtime calculator

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