MTTR (Mean Time To Repair)

The average time it takes to restore a failed asset to working order — a key maintainability metric that captures how fast your team responds.

Definition

MTTR stands for Mean Time To Repair: the average time it takes to restore a failed asset to working condition, measured from the moment it goes down to the moment it is back in service. It captures everything in between — diagnosis, waiting for parts, the actual repair, testing, and handback. A lower MTTR means faster recovery and less downtime.

MTTR formula

MTTR = total repair time ÷ number of repairs over a period. If a line suffered 4 failures last month and the total time-to-restore across them was 8 hours, MTTR is 2 hours. As with MTBF, the metric is only as reliable as the timestamps behind it — recording when work orders open and close in a CMMS is what makes MTTR measurable.

What drives MTTR up

The repair itself is often the smallest slice. The big drivers are usually waiting — for a technician to be notified, for the right parts to be on hand, for documentation or a manual, for an approval. That is why MTTR is as much a logistics and process metric as a wrench-time one: faster notification, better spare-parts stocking, and clear procedures cut it more than working faster ever could.

How to reduce MTTR

Tighten notification so the right technician knows quickly. Stock justified critical spares, attach approved manuals and procedures to assets, and capture failure history so repeat problems can be recognized. A CMMS can support those controls, but a lower MTTR must be demonstrated from consistent start and stop definitions and observed results rather than assumed from the software change alone.

What is included in MTTR?

Everything from failure to restored service: detection, diagnosis, waiting for parts or approvals, the repair, and testing. Much of MTTR is waiting, not wrench time.

How can I lower MTTR?

Speed up notification, stock critical spare parts, attach procedures and history to each asset, and track recurring failures — all of which a CMMS makes easier.