Uptime Reliability SLO/SLA Calculator
Calculate error budgets and allowed downtime from availability targets (Nines). Enter values for instant results with step-by-step formulas.
Formula
Allowed Downtime = Total Time × (1 - SLO%)
The Error Budget is the inverse of the Availability Target. For a standard 30-day window (43,200 minutes), a 99.9% target means 0.1% allowed downtime. 43,200 * 0.001 = 43.2 minutes. This budget is 'consumed' by incidents.
Worked Examples
Example 1: 3 Nines (99.9%)
Problem: 28 Day Window. Target 99.9%. Incident 10 mins.
Solution: Total Mins: 40,320. Allowed Down: 40.3 mins. Used: 10. Remaining: 30.3 mins.
Result: 40.3 Mins Budget (25% Burned)
Frequently Asked Questions
What is the difference between SLA and SLO?
SLO (Objective) is the internal target the engineering team aims for to keep users happy. SLA (Agreement) is the external contract with financial penalties if breached. The SLO should always be stricter than the SLA.
How do I get the most accurate result?
Enter values as precisely as possible using the correct units for each field. Check that you have selected the right unit (e.g. kilograms vs pounds, meters vs feet) before calculating. Rounding inputs early can reduce output precision.
Why might my result differ from another tool or reference?
Differences typically arise from rounding conventions, the specific version of a formula (for example, simple vs compound interest), or unit inconsistencies between inputs. Check that both tools are using the same formula variant and the same units. The References section links to the authoritative source behind the formula used here.
How do I interpret the result?
Results are displayed with a label and unit to help you understand the output. Many calculators include a short explanation or classification below the result (for example, a BMI category or risk level). Refer to the worked examples section on this page for real-world context.
Does Uptime Reliability SLO/SLA Calculator work offline?
Once the page is loaded, the calculation logic runs entirely in your browser. If you have already opened the page, most calculators will continue to work even if your internet connection is lost, since no server requests are needed for computation.
How do I verify Uptime Reliability SLO/SLA Calculator's result independently?
The Formula section on this page shows the equation used. You can reproduce the calculation manually or in a spreadsheet using those steps. Compare your answer against the worked examples in the Examples section, which use known reference values so you can confirm the calculator is behaving as expected.