Uptime SLA Calculator

About this calculator

This calculator converts an uptime SLA percentage — like the famous “three nines” (99.9%) or “five nines” (99.999%) — into the actual allowed downtime per year, month, and day, since a service-level agreement's percentage figure alone is hard to reason about without translating it into real time. For example, 99.9% availability allows about 8 hours 45 minutes of downtime per year, while 99.99% allows only about 52 minutes.

DevOps and site-reliability engineers use this to set realistic monitoring alerts and error budgets, IT procurement teams and contract managers use it to compare what different vendors' SLA percentages actually guarantee, and cloud service providers use it when drafting or negotiating SLA terms with customers. Anyone evaluating a hosting, SaaS, or cloud contract uses this calculator to understand exactly how much outage the fine print permits.