Variables
Description
What is this formula?
Mean Time To Repair (MTTR) measures the average time required to restore a failed asset, machine, or system to normal operation.
It is one of the most important maintainability indicators used in industrial maintenance.
When to use it
Use this formula when:
- Evaluating maintenance performance.
- Comparing repair efficiency.
- Estimating equipment downtime.
- Calculating operational readiness.
- Improving maintenance strategies.
Example
A production machine experiences:
Nr = 12 repairs
Total repair time:
Tr = 72 h
Formula:
MTTR = Tr/Nr
Substitution:
MTTR = 72/12
MTTR = 6 h
Result:
The average repair duration is 6 hours.
Applications
- Maintenance management
- Reliability engineering
- Asset management
- Downtime analysis
- Maintenance KPI reporting
Note
MTTR is an average performance indicator and may vary significantly depending on spare-part availability, technician skill, equipment complexity, and maintenance procedures. Different organizations may use slightly different MTTR definitions, so calculation methodology should be verified when comparing results.