Uptime Calculator
Explore SLA uptime levels and see exactly how much downtime each percentage allows. Then test your SLA math with a quiz.
SLA Uptime Percentage
Per Year
8h 45m 57s
Per Month
43m 49s
Per Week
10m 4s
Per Day
1m 26s
SLA Levels Comparison
Free-tier services, internal tools. Acceptable for non-critical workloads.
99% uptime means your service can be down for an entire long weekend each year.
Small business websites, development environments with SLA.
Cutting your allowed downtime in half from 99% still gives you almost 2 full days of downtime per year.
Most SaaS products target this. It's the most common commercial SLA.
Three nines is the sweet spot — achievable with good practices but still allows for planned maintenance windows.
Azure and AWS target this for many of their managed services.
At this level, a single 5-minute outage burns through your entire weekly error budget.
Financial systems, payment processors. Requires redundancy across availability zones.
Four nines means you have less than a minute of allowed downtime per week. Hope your deploys are fast!
Telecom networks, 911 systems. Requires active-active multi-region with automated failover.
Five nines is often called 'carrier-grade' availability. A single slow deploy could blow your annual budget.
Theoretical maximum. Some argue this is physically impossible for internet-connected services.
At six nines, if your health check takes longer than 2 seconds, you've already violated your monthly SLA.