Uptime & SLA Calculator
Enter any uptime percentage to see allowed downtime per day, week, month, and year
%
Common uptime SLAs:
Enter an uptime percentage to see results
The Nines Reference Table
How much downtime each SLA level actually allows:
| SLA | Per Year | Per Month | Per Week |
|---|---|---|---|
| 90% (one nine) | 36.5 days | 72 hours | 16.8 hours |
| 99% (two nines) | 3.65 days | 7.2 hours | 1.68 hours |
| 99.9% (three nines) | 8.77 hours | 43.8 min | 10.1 min |
| 99.99% (four nines) | 52.6 min | 4.38 min | 1.01 min |
| 99.999% (five nines) | 5.26 min | 26.3 sec | 6.05 sec |
| 99.9999% (six nines) | 31.6 sec | 2.63 sec | 0.6 sec |
Common Uptime Examples
99.9% Uptime (Three Nines)
≈ 43.8 minutes/month downtime
The most common SLA level for commercial cloud services and SaaS products. Good for most non-critical business applications.
99.99% Uptime (Four Nines)
≈ 4.38 minutes/month downtime
Expected for high-availability systems. Typical for enterprise-grade cloud platforms, payment processors, and critical APIs.
99.999% Uptime (Five Nines)
≈ 26.3 seconds/month downtime
The gold standard for mission-critical infrastructure — financial systems, emergency services, and telecom networks. Extremely difficult and expensive to achieve.
What is an Uptime SLA?
An uptime SLA (Service Level Agreement) is a contractual commitment from a vendor to keep their service available for a minimum percentage of time. If the vendor falls below the SLA threshold, customers typically receive service credits as compensation. Before signing a vendor contract, use this uptime calculator to convert their SLA percentage into actual allowed minutes of downtime per month — the number is often more meaningful than the percentage.
SRE and IT teams managing multiple vendors use tools like IsDown to monitor third-party status pages in one place and get alerts before vendor downtime impacts their users. Tracking SLA compliance across your vendor stack is much easier when you have a single dashboard rather than checking each vendor's status page manually.
Frequently Asked Questions
What does 99.9% uptime mean in minutes per month?
99.9% uptime allows approximately 43.8 minutes of downtime per month. This is sometimes called "three nines" and is the most common SLA level for commercial cloud services and SaaS products.
What is the difference between 99.9% and 99.99% uptime?
99.9% uptime (three nines) allows ~43.8 minutes of downtime per month, while 99.99% (four nines) allows only ~4.4 minutes. Each additional nine represents a 10x improvement in reliability and is significantly harder and more expensive to achieve.
How do I calculate uptime percentage from a downtime budget?
Divide your allowed downtime by the total time in the period, then subtract from 100%. For example, if you can tolerate 4 hours of downtime per month: (4 / 720) × 100 = 0.556%, so your required uptime is 100% − 0.556% = 99.44%. Use the Reverse Calculator tab above to do this automatically.
What does five nines uptime mean?
Five nines refers to 99.999% uptime, which allows only about 26 seconds of downtime per month or ~5.26 minutes per year. It is considered the gold standard for mission-critical infrastructure such as financial systems, telecom networks, and emergency services.
What is considered good uptime for a SaaS product?
For most SaaS products, 99.9% uptime is considered the baseline expectation. Enterprise customers often require 99.99% or higher SLAs. If your product depends on third-party services, their uptime directly affects yours — which is why monitoring your entire vendor stack matters, not just your own infrastructure.
The Status Page Aggregator with Early Outage Detection
Monitoring all vendors in one place
Real-time Slack alerts when outages occur
Create internal & external status pages
Weekly email reports of vendor performance