# MTTR

**URL:** https://kaizumi.com/dictionary/mttr

**Description:** MTTR (Mean Time To Repair) measures average maintenance responsiveness by calculating the average time to restore failed equipment to operation.

**Category:** tpm

**Tags:** metrics, equipment, foundational

## Definition

MTTR (Mean Time To Repair) is a maintainability metric that measures the average time required to restore failed equipment to normal operation. It includes the entire restoration process: failure detection, response, diagnosis, repair execution, and verification. Lower MTTR indicates faster recovery capability. MTTR complements MTBF—together they determine equipment availability. Improving MTTR requires attention to spare parts availability, technician skills, diagnostic aids, and equipment accessibility.

## Examples

### Manufacturing

> Analyzing breakdown data, a team found average repair time of 4 hours. Breaking down MTTR: 30 minutes to detect failure, 45 minutes for technician response, 90 minutes diagnosis, 60 minutes repair, 15 minutes verification. They reduced response time with dedicated maintenance and cut MTTR to 2.5 hours.

### Healthcare

> Medical equipment repairs averaged 6 hours MTTR. Analysis showed 2 hours waiting for parts from central storage. Implementing point-of-use spare parts storage reduced wait time to 20 minutes and overall MTTR to 4 hours.

### Administrative

> Server restoration averaged 90 minutes. Breakdown: 10 minutes detection, 15 minutes response, 30 minutes diagnosis, 25 minutes repair, 10 minutes verification. Automated monitoring cut detection to 2 minutes; better documentation reduced diagnosis to 15 minutes. New MTTR: 65 minutes.

## Key Points

- MTTR = Total Repair Time / Number of Repairs
- Lower MTTR indicates faster recovery capability
- Includes detection, response, diagnosis, repair, and verification time
- Availability = MTBF / (MTBF + MTTR)

## Common Misconceptions

**MTTR only measures repair skill.** MTTR includes the entire restoration cycle—waiting time, travel time, and parts availability often dominate actual repair time. Reducing MTTR requires systemic improvements, not just faster hands-on work.

**Reducing MTTR is always beneficial.** Very low MTTR might indicate excessive maintenance resources or premature return to service. The goal is optimal MTTR that balances restoration speed with resource cost and repair quality.

## Related Tool

Break maintenance response into its component activities and chart each step's time against takt time using the [Yamazumi tool](/tools/yamazumi).

Source: https://kaizumi.com/dictionary/mttr
Licence: free to quote and cite with attribution to Kaizumi.