MTTR measures maintainability — how quickly you get equipment working again. It usually runs from when the failure is reported (or detected) to when the asset is back in service, including diagnosis, waiting for parts, repair and testing. Define the start and end points consistently.
Formula
MTTR = total repair (downtime) time ÷ number of repairs
Worked example
Three repairs last quarter took 2 h, 4 h and 3 h.
MTTR = (2 + 4 + 3) ÷ 3 = 3 hours.
Why it matters
High MTTR points to slow response, missing spare parts, poor documentation or hard-to-find assets. Reducing it cuts downtime directly. Being able to locate the asset and see its history instantly — for example by scanning its tag — removes one common delay.
Note that "MTTR" is used for slightly different measures — mean time to repair, to recover, to restore or to respond — so check which one a report means before comparing figures.