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MTBF and MTTR Metrics

MTBF and MTTR are key maintenance metrics that help you understand asset reliability and repair efficiency. Zeltask calculates these automatically based on downtime events recorded for each asset.

What Is MTBF?​

MTBF (Mean Time Between Failures) measures how long an asset operates before a failure occurs.

  • What it indicates: Asset reliability
  • Higher is better: More time between failures means more reliable equipment
  • Based on: Time elapsed between unplanned downtime events

How MTBF Is Calculated​

MTBF = Total Operating Time / Number of Failures

Example: An asset operated for 720 hours and experienced 3 failures. MTBF = 720 / 3 = 240 hours between failures on average.

What Is MTTR?​

MTTR (Mean Time to Repair) measures the average time required to repair an asset after an unplanned failure.

  • What it indicates: Repair efficiency
  • Lower is better: Less repair time means faster recovery
  • Based on: Duration of unplanned downtime events

How MTTR Is Calculated​

MTTR = Total Repair Time / Number of Repairs

Example: An asset had 3 failures with repair times of 2, 4, and 3 hours. MTTR = (2 + 4 + 3) / 3 = 3 hours average repair time.

Why These Metrics Matter​

MetricWhat It Tells YouAction If Poor
MTBFHow reliable the asset isReview preventive maintenance frequency, consider equipment upgrade
MTTRHow quickly you recover from failuresImprove spare parts availability, train technicians, review procedures

Using MTBF and MTTR Together​

  • High MTBF + Low MTTR: Ideal — reliable equipment with fast repairs when needed
  • Low MTBF + Low MTTR: Equipment fails often but recovers quickly — focus on prevention
  • High MTBF + High MTTR: Rarely fails but takes long to fix — improve repair readiness
  • Low MTBF + High MTTR: Critical concern — equipment is unreliable and slow to repair

Requirements for Accurate Metrics​

For Zeltask to calculate MTBF and MTTR accurately:

  1. Enable downtime tracking for the asset
  2. Record downtime events consistently:
    • Log when assets go offline (planned or unplanned)
    • Log when assets return to online status
  3. Distinguish planned vs. unplanned downtime:
    • Only unplanned downtime affects MTBF and MTTR
    • Planned maintenance should be marked accordingly

Viewing MTBF and MTTR​

  1. Open the Assets module
  2. Select an asset to view its detail page
  3. Access the reliability metrics in the asset's performance section
  4. Use time filters to view metrics over different periods:
    • 1 week
    • 3 months
    • 6 months
    • 1 year

[Screenshot: Asset detail view showing MTBF and MTTR metrics]

Lifespan Considerations​

Metrics can be calculated from:

  • Asset creation date: Includes all historical data
  • Downtime tracking enabled date: Only includes data from when tracking started

Review your settings to understand which baseline is being used.

Tips for Improving Metrics​

To Improve MTBF (Increase Reliability)​

  • Implement or increase preventive maintenance frequency
  • Address root causes of recurring failures
  • Upgrade aging or unreliable components
  • Improve operating conditions (temperature, humidity, cleanliness)

To Improve MTTR (Reduce Repair Time)​

  • Keep critical spare parts in stock
  • Document common repair procedures
  • Train technicians on frequent failure modes
  • Pre-position tools and materials near critical assets