SLA Uptime Calculator
Convert SLA uptime (99.9%, 99.99%, five nines) into allowed downtime per day, week, month, and year, or measure achieved availability from real downtime.
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What is SLA Uptime Calculator?
An SLA uptime calculator converts a service-level availability target such as 99.9% into the exact downtime allowed per day, week, month, and year. It also works in reverse, turning measured downtime into the availability you actually achieved, so you can check whether an incident stayed inside your SLA budget.
Key Benefits
- Concrete downtime budgets in minutes
- Reverse mode for incident reviews
- Standard 30-day month and 365-day year
- Tier table from 99% to five nines
- Runs offline, nothing uploaded
Common Use Cases
- •Reviewing hosting or API SLAs
- •Post-incident availability reports
- •Setting SRE error budgets
- •Comparing provider reliability
- •Drafting service contracts
How to Use the SLA Uptime Calculator
- Enter SLA target: Type the uptime percentage your provider promises, e.g. 99.9.
- Calculate downtime: Click Calculate to see allowed downtime per day, week, month, and year.
- Verify real incidents: Switch to Downtime to Availability mode, enter measured minutes and the period.
- Compare against SLA: Check the achieved availability against the tier table and your contract terms.
Key Features
- Convert any uptime percentage into allowed downtime
- Day, week, month, and year periods
- Reverse mode: downtime to achieved availability
- Built-in 99% to 99.999% tier reference table
- Copy results for tickets, reports, and SLA reviews
Frequently Asked Questions
How much downtime is 99.9% uptime?
With a 30-day month (43,200 minutes), 99.9% uptime allows 43.2 minutes of downtime per month — about 10 minutes per week or 8.76 hours per year.
What are three nines, four nines, and five nines?
They are shorthand for 99.9%, 99.99%, and 99.999% availability, which allow 43.2, 4.32, and 0.43 minutes of downtime per 30-day month respectively.
Does this tool count a 30-day or 31-day month?
It uses a 30-day month (43,200 minutes) and a 365-day year (525,600 minutes), the most common convention in provider SLAs. For a 31-day month, scale the result by 31/30.
What is the difference between SLO and SLA here?
An SLA is the contractual commitment with penalties; an SLO is your internal target. The math is the same — enter either percentage and read the allowed downtime as your error budget.