# Mean Time Between Failures (MTBF)

The most widely used metrics for tracking the reliability of process machinery throughout the industry. To calculate, take the number of failures in a given time period and the total number of machines in the population.

where M is the total machine count; T is the reporting time; and R is the total number of repairs during the reporting period. (Example: There are 200 pumps in a population that experiences 20 failures in a three-month period. This group of pumps has a MTBR of 200 Ã— 3/20, or 30 months between repairs.)