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The fast lane for the math you almost remember from school. Type the numbers, get the answer, move on with your day.
Try a scenario
Click to load — tweak from there.Inputs
Result
Allowed downtime per month
43.8
Allowed downtime per year
526.0
Allowed downtime per week
10.1
Allowed downtime per day
1.44
Actual uptime % (if downtime entered)
99.9000%
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How to use this
- 1Enter sla uptime percentage (%).
- 2Enter actual downtime this month (optional) (minutes).
- 3Read your allowed downtime per month on the right — it updates as you type.
- 4Hit Share to keep the scenario or send it to someone.
About this calculator
SLA percentages like 99.9% or 99.99% sound similar but represent very different amounts of allowed downtime once converted into actual minutes, and this is the single most common misunderstanding in vendor contract negotiations. This calculator converts any uptime percentage into allowed downtime per year, month, week, and day, so you can compare an SLA to your actual operational needs — a 99.9% SLA (three nines) allows 8.77 hours of downtime a year, while 99.99% (four nines) allows only 52.6 minutes, and 99.999% (five nines) allows just 5.26 minutes. It also computes the reverse: given actual downtime minutes over a period, what SLA percentage that represents, which is what you need when reporting real uptime against a contracted target.
Worked example
Using the values the calculator loads with:
Inputs
- SLA uptime percentage: 99.9 %
- Actual downtime this month (optional): 0 minutes
Results
- Allowed downtime per month: 43.8
- Allowed downtime per year: 526
- Allowed downtime per week: 10.1
- Allowed downtime per day: 1.44
- Actual uptime % (if downtime entered): 99.9000%
What each field means
Inputs
- SLA uptime percentage (%)
- The sla uptime percentage used in the calculation, measured in %. Starts at 99.9 % so you have a working example on load. Accepted range: 0–100 %.
- Actual downtime this month (optional) (minutes)
- The actual downtime this month (optional) used in the calculation, measured in minutes. Starts at 0 minutes so you have a working example on load.
Results
- Allowed downtime per month
- Returned as a length of time and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Allowed downtime per year
- Returned as a length of time. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Allowed downtime per week
- Returned as a length of time. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Allowed downtime per day
- Returned as a length of time. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Actual uptime % (if downtime entered)
- Returned as a percentage. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
What's the practical difference between three and four nines?
99.9% allows 43.2 minutes of downtime a month; 99.99% allows only 4.3 minutes. That 10x tighter budget typically requires multi-AZ or multi-region failover, automated rollback, and sub-minute detection and paging — going from three to four nines is usually a multi-quarter engineering investment, not a config change, and it should be priced accordingly when negotiated into a contract.
Does scheduled maintenance count against the SLA?
It depends entirely on the contract language. Most vendor SLAs explicitly exclude 'planned maintenance windows' announced with advance notice (commonly 24-72 hours) from the downtime calculation, so read the exclusions clause carefully — an SLA that looks strict on paper can have generous carve-outs that make it far weaker in practice.
How do SLA credits typically work when the target is missed?
Most cloud and SaaS SLAs offer service credits, not cash refunds, calculated as a percentage of the monthly bill and scaled to how badly the target was missed — for example 10% credit for uptime between 99.0-99.9% and 25-30% credit below 99.0%. Credits are capped and require you to file a claim within a set window, so track downtime yourself; providers don't proactively issue credits in most cases.
Accuracy and limitations
- Results are rounded for display; the underlying calculation keeps full precision.
- Very large or very small inputs may hit floating-point limits in the browser.
- Inputs outside the accepted range are clamped rather than rejected.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). SLA Uptime to Downtime Minutes Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/sla-uptime-downtime
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/sla-uptime-downtime" target="_blank" rel="noopener">SLA Uptime to Downtime Minutes Calculator — RevenueLab</a> (2026).</p>
Source: [SLA Uptime to Downtime Minutes Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/sla-uptime-downtime) (2026).