SLA Uptime Calculator
What does “99.9% uptime” actually mean for your service? Enter any SLA percentage to see the maximum allowed downtime per day, month, and year.
% uptime
90%99.999%
Downtime per Day
1m
1.44 minutes
Downtime per Month
43m
43.2 minutes
Downtime per Year
8h 46m
526 minutes
| SLA | Daily | Monthly | Yearly |
|---|---|---|---|
| 99% | 14m | 7h 12m | 3d 15h 36m |
| 99.5% | 7m | 3h 36m | 1d 19h 48m |
| 99.9% | 1m | 43m | 8h 46m |
| 99.95% | 43.2s | 22m | 4h 23m |
| 99.99% | 8.6s | 4m | 53m |
| 99.999% | 0.9s | 25.9s | 5m |
Understanding SLA Uptime Percentages
Service Level Agreements (SLAs) define the expected uptime for a service. While 99.9% sounds nearly perfect, it still allows for 8 hours and 46 minutes of downtime per year. For businesses depending on multiple APIs, these windows compound.
The “Nines” Explained
- Two nines (99%) — 3.65 days/year downtime. Acceptable for internal tools.
- Three nines (99.9%) — 8h 46m/year. Standard for most SaaS APIs.
- Four nines (99.99%) — 52.6 min/year. Premium tier at AWS, Stripe, etc.
- Five nines (99.999%) — 5.26 min/year. Enterprise-grade, extremely expensive.
Why This Matters for API Monitoring
If your app depends on 5 APIs each with 99.9% SLAs, the combined probability of at least one being down is significantly higher than any individual SLA suggests. This is why monitoring third-party API status is critical — you need to know the moment a dependency fails.
API Status Check monitors 100+ APIs in real-time, so you know before your users do.