Mean Time Between Failures (MTBF)

Mean time between failures is the average operating time between consecutive failures of a repairable asset, calculated as total uptime divided by the number of failures. A higher MTBF indicates greater reliability.

MTBF applies to assets that are repaired and returned to service, distinguishing it from mean time to failure for non-repairable items. It is a headline reliability metric used to compare equipment, plan spares and set maintenance intervals, but it must be read carefully: an average hides the failure distribution, so two machines with the same MTBF can behave very differently. It is most meaningful within the constant-failure-rate phase of an asset's life.

Related terms

MTTR (Mean Time To Repair) · Bathtub Curve · Weibull Analysis

Where this applies

Running a bad-actor review meeting · Run-to-Failure vs Preventive Maintenance