PowersYourTeam

Understanding the Metrics

Key Formulas

MTBF = Total Operating Time ÷ Number of Failures

Mean Time Between Failures (hours)

MTTR = Total Repair Time ÷ Number of Repairs

Mean Time To Repair (hours)

Availability = MTBF ÷ (MTBF + MTTR) × 100%

Percentage of time equipment is available

Failure Rate (λ) = 1 ÷ MTBF

Failures per hour

💡 Metric Definitions

MTBF: Average operating time between failures (repairable systems)
MTTF: Average time to failure (non-repairable items)
MTTR: Average time to restore equipment after failure
Availability: % of time equipment can perform its function

Calculation Method

Total Operating Time Hours the equipment ran (not counting downtime)

Number of Failures Total unplanned breakdowns

Total Repair Time Total hours spent on repairs

Time Period Analysis time frame

Quick Examples

Calculated Reliability Metrics

MTBF

1,460

hours

≈ 60.8 days between failures

MTTR

8.0

hours

Average repair duration

Availability

99.46

Equipment uptime percentage

Failure Rate (λ)

0.00068

failures/hour

6.0 failures per year

Availability Scale

0% 50% 75% 90% 95% 99% 100%

Uptime vs Downtime Distribution

99.46% Uptime

Operating Time: 8,712 hrs

Downtime: 48 hrs

"Nines" of Availability

Annual Downtime: 47.3 hours/year

📊 Industry Benchmarks

World Class

> 99%

Good

95-99%

Average

90-95%

Needs Improvement

< 90%

Your availability: World Class

Improving Your Metrics

📈 Increase MTBF

Implement predictive maintenance (PdM)
Improve lubrication practices
Address root causes of failures
Upgrade to more reliable components
Optimize operating conditions

⏱️ Reduce MTTR

Stock critical spare parts on-site
Train technicians on common repairs
Create standard repair procedures
Improve fault detection & diagnosis
Pre-stage tools and equipment

🎯 Availability Impact

To improve availability: Focus on the metric with the biggest impact. If MTTR is already low, improving MTBF has more effect. If failures are rare but repairs take days, focus on reducing MTTR.

Rule of thumb: A 10% MTBF improvement has roughly the same effect as a 10% MTTR reduction.