Uptime Calculator
Calculate allowed downtime for any uptime SLA percentage — 99.9%, 99.99%, 99.999% and more
Uptime Percentage
3 nines — common SLA tier
Allowed Downtime (99.9% uptime)
Per Day
1m 26s
Per Week
10m 5s
Per Month
43m 12s
Per Year
8h 46m
SLA Tier Comparison
| Uptime | Per Day | Per Week | Per Month | Per Year |
|---|---|---|---|---|
| 90% | 2h 24m | 16h 48m | 3d | 36d 12h |
| 95% | 1h 12m | 8h 24m | 1d 12h | 18d 6h |
| 99% | 14m 24s | 1h 41m | 7h 12m | 3d 16h |
| 99.5% | 7m 12s | 50m 24s | 3h 36m | 1d 20h |
| 99.9% | 1m 26s | 10m 5s | 43m 12s | 8h 46m |
| 99.95% | 43.2 sec | 5m 2s | 21m 36s | 4h 23m |
| 99.99% | 8.6 sec | 1 min | 4m 19s | 52m 34s |
| 99.999% | 864 ms | 6.0 sec | 25.9 sec | 5m 15s |
Frequently asked questions
What does 99.9% uptime mean in hours?
99.9% uptime ("three nines") allows roughly 8.76 hours of downtime per year, 43.8 minutes per month, or about 10 minutes per week.
What is the difference between 99.99% and 99.999% uptime?
99.99% ("four nines") allows ~52 minutes of downtime per year. 99.999% ("five nines") allows only ~5 minutes per year — a significant jump that typically requires redundant infrastructure and automated failover.
How is uptime percentage calculated?
Uptime % = (total time − downtime) / total time × 100. For SLA purposes, downtime is usually measured as unplanned outage time within a calendar month or year.
What is a good uptime SLA for a web application?
Most cloud providers target 99.9% to 99.99%. Consumer apps often accept 99.9%, while mission-critical systems (payments, healthcare) typically require 99.99% or higher.