Mean Time To Repair (MTTR): What It Measures, and How It Differs from MTBF
Mean time to repair, or MTTR, is the average time it takes to get failed equipment running again, from the moment it goes down to the moment it’s back in service. It gets read as just wrench time, but a full MTTR covers detection, diagnosis, the fix and the test. It’s the recovery half of reliability; MTBF is the uptime half.
Why does MTTR matter?
MTTR matters because it measures how quickly you recover when equipment fails, and every extra hour of repair is an extra hour of lost production. Tracking the full picture, from detection through diagnosis, repair and test, shows where recovery time is really being lost, not just time on the tools. Cut MTTR and you cut downtime and lift machine availability, without changing how often things break.
What does MTTR actually include?
A useful MTTR counts the whole outage, not just the time on the tools:
- Detecting the failure, which is where a slow alarm quietly inflates the number.
- Diagnosing what went wrong.
- The physical repair itself.
- Testing and restoring the equipment to service.
- Any wait for parts or a technician, if you’re measuring the honest version.
How does MTTR differ from MTBF and MTTD?
MTTR vs MTBF vs MTTD at a glance
Three clocks in the same failure cycle.
| Metric | Measures | When |
|---|---|---|
| MTTD | Time to detect a failure | Before the repair starts |
| MTTR | Time to repair and restore | During the outage |
| MTBF | Uptime between failures | Between outages |
Related Terms
- Mean Time to Failure (MTTF) – average life of a non-repairable item.
- Machine Availability – driven by MTBF and MTTR together.
- Troubleshooting
Further Reading
- Maintenance Management Software (CMMS) – maintenance digital