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MTBF & System Availability Calculator

Calculate Mean Time Between Failures (MTBF), system availability percentage, and expected annual downtime.

Total hours the system has been operational (8760 = 1 year).
Total number of failures/outages in the operating period.
Mean Time To Repair (MTTR) � average hours to restore service after each failure.

Results

Mean Time Between Failures2,920.0 hrs
Availability99.863%
Expected Annual Downtime12.0 hrs/year

📖What is it?

For informational/educational purposes only. MTBF (Mean Time Between Failures) measures the average time a system operates before a failure occurs. System availability is the percentage of time the system is operational, calculated from MTBF and MTTR.

🎯How to use

Enter the total hours the system has operated, the number of failures during that period, and the average time to repair each failure. The calculator outputs MTBF, availability %, and expected annual downtime.

💡Example scenario

A server runs 8,760 hours/year with 3 failures and 4-hour average repair time. MTBF = 2,920 hrs. Availability = 2920 / (2920 + 4) � 100 = 99.863%. Expected annual downtime = 12 hours.

🏆Pro tip

To achieve four nines (99.99%) availability, you need MTBF/MTTR > 9,999. Redundancy (active-active clusters) improves system MTBF multiplicatively. Focus MTTR improvements on runbooks, automation, and on-call response processes.