9 Key Maintenance Metrics and KPIs to Track and Improve Performance
Maintenance KPIs (Key Performance Indicators) are measurable benchmarks used in maintenance management to track how effectively asset management works and how well maintenance activities support operational priorities.
For maintenance managers, KPIs convert routine maintenance activities into measurable outcomes that reflect asset reliability, downtime exposure, and alignment with business goals. Knowing which KPIs and metrics to track is therefore the first step toward using maintenance data effectively.
In this blog, we cover the 9 commonly used maintenance metrics and KPIs, which are:
- Mean Time to Repair (MTTR)
- Emergency Work Orders (EWOs)
- Mean Time Between Failures (MTBF)
- Overall Equipment Effectiveness (OEE)
- Maintenance Backlogs
- Preventive Maintenance Compliance
- Planned Maintenance Percentage (PMP)
- Lost Time Injury Frequency Rate (LTIFR)
- Stock Turnover Ratio
How Are Maintenance KPIs Different From Maintenance Metrics?
Maintenance KPIs and maintenance metrics get used interchangeably, but they serve different roles in how maintenance performance is tracked and interpreted. The core difference lies in intent. KPIs are tied to clearly defined goals and tell whether maintenance efforts are contributing to broader operational or business objectives. Metrics, on the other hand, simply record what is happening on the ground.
KPIs exist to support decisions. Leadership teams rely on them to judge whether maintenance strategies are working as planned and where corrective action may be needed. Metrics support that process indirectly by offering detailed operational data. They help teams understand workload, efficiency, and execution, but they do not automatically signal success or failure.
The level of focus also separates the two. KPIs look at outcomes such as asset availability, maintenance cost as a percentage of asset value, or unplanned downtime. Metrics concentrate on processes like mean time to repair (MTTR), number of work orders completed, or labor hours logged.
Because of this difference, the audience changes as well. KPIs matter more to managers and executives tracking performance trends, while metrics are most valuable to technicians and supervisors managing daily maintenance activities.
9 Commonly Used Maintenance Metrics
We discuss the importance of these maintenance performance metrics and also cover the process to implement and track them.
1. Mean Time to Repair (MTTR)
Mean Time to Repair (MTTR) measures the average time required to restore equipment to operational condition after a failure occurs.
Formula:
MTTR = Total repair time / Total number of repairs
MTTR gives insights into how efficiently maintenance teams diagnose issues, mobilize resources, and complete repairs. Lower MTTR values indicate faster recovery, reduced production interruptions, and better coordination between maintenance and operations. Higher MTTR values signal delays caused by spare part shortages, skill gaps, or inefficient workflows.
Tracking mean time to repair (MTTR) over time helps organizations assess repair responsiveness, identify bottlenecks in maintenance execution, and improve downtime management strategies.
2. Emergency Work Orders (EWOs)
Emergency Work Orders (EWOs) represent unplanned maintenance activities that require immediate action to avoid equipment damage, safety risks, or operational stoppages.
Formula:
EWOs = Total emergency work orders / Total number of work orders
EWOs serve as an indicator of how often assets fail unexpectedly and how reactive a maintenance operation has become. A consistently high EWO ratio points to weak preventive maintenance coverage, aging equipment, or poor failure detection practices. Reducing EWOs allows maintenance teams to shift effort toward planned work, improve asset reliability, and stabilize maintenance schedules.
3. Mean Time Between Failures (MTBF)
Mean Time Between Failures (MTBF) measures the average operational time an asset runs before experiencing a failure.
Formula:
MTBF = Total operational hours / Total number of failures
MTBF gives an idea about asset reliability and the long-term effectiveness of maintenance strategies. Higher mean time between failures (MTBF) indicate stable equipment performance and fewer unexpected breakdowns. Lower MTBF values suggest frequent failures, highlighting the need for improved preventive maintenance, condition monitoring, or asset replacement planning. MTBF is widely used to evaluate progress in reducing downtime.
4. Overall Equipment Effectiveness (OEE)
Overall Equipment Effectiveness (OEE) is a maintenance KPI that evaluates how effectively equipment is utilized by measuring availability, performance efficiency, and output quality.
Formula:
OEE = Availability × Performance × Quality
OEE provides a consolidated view of operational losses caused by downtime, speed reductions, and quality defects. Higher OEE values indicate stronger coordination between production and maintenance teams. Industry benchmarks suggest that proactive maintenance practices contribute significantly to achieving overall equipment effectiveness (OEE) levels above 90%, while lower values highlight opportunities for improving asset availability and process stability.
5. Maintenance Backlogs
Maintenance Backlogs represent the volume of approved maintenance work that remains incomplete within a given period.
Formula:
Maintenance backlog = Number of pending work orders / Total number of work orders
A growing backlog indicates capacity constraints, inefficient scheduling, or resource shortages. Excessive backlog levels increase the risk of deferred maintenance, unplanned downtime, and higher long-term repair costs. Maintaining a balanced backlog requires prioritizing critical tasks, aligning labor availability with workload, and improving work order planning accuracy.
6. Preventive Maintenance Compliance
Preventive Maintenance Compliance (PMC) measures how consistently scheduled preventive maintenance tasks are completed within the planned time frame.
Formula:
PMC = (Number of PM tasks completed on schedule / Total number of PM tasks) × 100
PMC reflects the discipline and execution strength of a preventive maintenance program. Industry guidelines recommend completing PM tasks within 10% of the planned interval, such as finishing monthly tasks within three days of the scheduled date. Higher preventive maintenance values (PMC) values indicate reliable execution and better resource utilization, while lower values signal scheduling gaps or workload imbalance.
7. Planned Maintenance Percentage (PMP)
Planned maintenance percentage is a measure of the percentage of maintenance tasks that are planned and scheduled in advance. It’s a maintenance key performance indicator that works like a forecast for maintenance work that needs to be carried out in the future.
Formula:
PMP = Planned maintenance hours / Total maintenance hours × 100
Tracking PMP enables maintenance teams to identify areas for improvement and optimize maintenance processes further. For example, if PMP is low, maintenance teams may need to adopt more preventive maintenance measures or improve scheduling practices. Planned maintenance percentage (PMP) values over 90% are described as world-class maintenance, whereas values over 70% are acceptable.
8. Lost Time Injury Frequency Rate (LTIFR)
Lost Time Injury Frequency Rate (LTIFR) is a maintenance KPI that measures the number of work-related injuries that result in lost work time per a standardized number of labor hours worked. It is a key safety performance indicator used to assess how effectively workplace risks are being managed.
Formula:
LTIFR = (Number of lost time injuries × 1,000,000) / Total hours worked
LTIFR highlights the relationship between maintenance activities and workforce safety. A rising LTIFR points to unsafe work practices, inadequate training, poor lockout-tagout procedures, or insufficient equipment condition monitoring. Lower LTIFR values indicate stronger safety controls, better compliance with procedures, and reduced operational disruptions caused by injury-related absences.
9. Stock Turnover Ratio
Stock Turnover Ratio is also a KPI that measures how frequently inventory items, such as spare parts and consumables, are used and replenished over a specific period. In maintenance operations, it shows how efficiently spare parts inventory supports asset uptime.
Formula:
Stock Turnover Ratio = Cost of spare parts used / Average inventory value
A balanced stock turnover ratio indicates effective inventory planning—critical spares are available when needed without tying up excess capital. Low turnover may signal overstocking, obsolete parts, or inaccurate demand forecasting, while very high turnover can increase the risk of stockouts and extended repair times.
How to Select Right KPIs For Your Maintenance Operations
KPIs should translate maintenance strategy into measurable signals that reflect how well assets, teams, and processes perform over time, without creating reporting noise or misaligned incentives. To unfold this reality, following considerations are important when selecting the right maintenance KPIs:
- Align KPIs with maintenance objectives:
Choose metrics that directly reflect goals such as uptime improvement, failure reduction, or lifecycle cost optimization rather than generic performance indicators.
- Map KPIs to asset criticality:
High-criticality assets require reliability and risk-focused KPIs, while non-critical assets may only need cost and schedule adherence metrics.
- Balance leading and lagging indicators:
Combine outcome-based KPIs like MTBF or downtime with predictive indicators such as preventive maintenance compliance or backlog health.
- Use data that is consistently measurable:
Select KPIs supported by reliable CMMS, EAM, or sensor data to avoid manual estimation and reporting gaps.
- Keep KPIs actionable for maintenance teams:
Metrics should clearly indicate where corrective action is needed, not just describe historical performance.
- Limit the number of KPIs tracked:
Focus on a concise set that provides operational visibility without overwhelming planners, technicians, or managers.
- Review and recalibrate KPIs periodically:
Maintenance maturity, asset age, and operational priorities change, requiring KPI thresholds and relevance to be reassessed.
How Do You Track and Measure Maintenance KPIs?
Implementing and tracking the right metrics is key to effective maintenance. Here’s how you can go about it.
- Start by Defining:
Start by getting clear on what actually needs tracking and why it matters. Decide what each metric should improve—less downtime, longer asset life, faster response times. Group metrics into operational and financial categories, then connect them directly to business priorities so the data supports real decisions, not just reporting.
- Identify and Proceed:
Move next to how those metrics will be captured. Use CMMS platforms, automated sensors, or IoT systems to collect data consistently and at scale. In smaller setups, track select metrics manually where it makes sense. Whatever the method, apply the same measurement rules across teams to avoid skewed results.
- Benchmark to Succeed:
Put your numbers into context by benchmarking them. Compare current performance with industry standards, past internal results, or similar organizations. These comparisons reveal whether performance is improving and where maintenance practices fall short.
- Set a Schedule for Data Collection:
Create a clear rhythm for collecting data. Tie event-based metrics like downtime to failures or maintenance activities, and review performance metrics at fixed intervals such as weekly or monthly. Make expectations clear so teams follow the schedule without reminders.
- Gather and Extract:
Collect data carefully and consistently. Rely on automation where possible, train technicians on proper data entry, and review records regularly. Clean, accurate data makes analysis meaningful and avoids wrong conclusions.
- Unearth and Explore:
Dig into the data to spot patterns and recurring issues. Look beyond surface-level numbers to identify root causes behind failures, delays, or rising costs. Use trend analysis and simple statistical tools to focus attention on issues that impact reliability and productivity.
- Communicate to Help Interpret:
Share insights in a way that drives action. Use dashboards and visual reports to make results easy to understand, discuss findings regularly with teams and leadership, and turn insights into changes – whether that means adjusting maintenance schedules, improving workflows, or upgrading assets.
Takeaway
These are important maintenance metrics that offer crucial insights about equipment performance and reliability.
