Mean Time to Failure (MTTF) and sometimes references as Mean Time For Failure (MTFF) is the length of time a device or software is expected to last in operation. MTTF is one of many ways to assess the reliability of pieces of hardware or other technology. MTTF is used for only products or services that are non-repairable, meaning once they fail they’re finished. In comparison to MTTF, Mean Time Between Failures is a related concept for repairable devices. Finally Mean Time To Repair is yet a third concept that applies a schedule for which equipment must be serviced before failure is likely to occur. For this article CyberHoot focuses solely on MTTF.
As a metric, MTTF represents how long a product can reasonably be expected to perform based on specific testing. This data is often collected by running many devices, even thousands of devices, for a specific number of hours.
One of the main situations where MTTF is extremely important is when hardware or other technology are used in aerospace or military missions. It becomes valuable to know about general reliability for these items when people’s lives may depend on it. For non-repairable items, MTTF is a statistic that is of great interest to engineers and others assessing these pieces as parts of larger systems.