5 Important Maintenance Metrics and How To Use Them

Effective maintenance of equipment is a critical factor in delivering quality operations that provide timely resources at a minimal cost. However, those in the maintenance field understand that equipment reliability does not come easy. 

Organizations need to set quality benchmarks to measure the current effectiveness and predict future performance and use the data obtained to understand where to make improvements.  

One way to do this is by using different maintenance metrics to understand the equipment performance. These metrics are very important as they can mean the difference between achieving the overall business goals and explaining how unexpected breakdowns caused yet another production delay.  

What are the maintenance metrics?

There are two categories of maintenance key performance indicators which include the leading and lagging indicators. The leading indicators signal future events and the lagging indicators follow the past events. 

The leading indicator comprises from metrics like the Estimated vs actual performance and PM Compliance, while the lagging indicatorare reflected in maintenance metrics like the Mean Time To Repair (MTTR) , Overall Equipment Effectiveness OEE and Mean time between failure (MTBF). 

Using these maintenance metrics and turning the data into actionable information, organizations can acquire both qualitative and quantitative insights. 

And there is no better way to spot opportunities for improvement.

Here are some important maintenance metrics you should track if you want to improve and optimize your maintenance operations.

1. Planned maintenance percentage (PPC)

This metrics represents the percentage of time spent on planned maintenance activities against the unplanned. 

In simpler terms, this metric tells you how much maintenance work  done on a particular asset was a part of your  preventive maintenance plan versus how much time you’ve spent repairing it because it unexpectedly broke down.

In a great system, 90% of the maintenance should be planned. 

The calculation is as follows:

PPC= (scheduled maintenance time/total maintenance hours) x 100

2. Overall Equipment Effectiveness (OEE)
OEE is the measure of the productivity of a piece of equipment. It gives informed data on how effective organization’s maintenance processes is running based on factors like equipment quality, performance, and availability. 

A 100% OEE means that your system is producing no defects, as fast as possible, and with no stops in the production.

understanding OEE and the  underlying losses , organizations can gain significant insights into how to improve their manufacturing processes. Using this metric, you can identify what has a negative impact on your production, so you can eliminate it.

To calculate the OEE, you multiply the availability by the performance and quality :

OEE = availability x performance x quality

3. Mean time to repair (MTTR)

MTTR is the measure of the repairable items maintainability

The MTTR clock starts ticking when the repairs start and it goes on until operations are restored. This includes repair time, testing period, and return to the normal operating condition.

The goal of every organizations is to reduce MTTR as much as possible. This is especially important for critical assets as ever additional hour you need to restore an asset to a working condition amount to huge losses for your firm.

To calculate MTTR, you divide the downtime period by the total number of downtimes:

MTTR= (SUM of downtime periods/ total number of repairs)

4. Mean time between failure (MTBF)

MTBF is the measure of the predicted time between one breakdown to the next during normal operation. 

In essence, MTBF tells you the expected lifetime for a specific piece of equipment. Higher MTBF means that the part (or product) you bought will work longer before it experiences failure.

If you know how long a specific part/equipment will last, it gets much easier to predict and prepare for a failure or schedule some preventive work.

To calculate the MTBF, you divide the total operational time by the number of failures:

MTBF= (SUM of operational time/total number of failures)

5. Preventive maintenance compliance (PMC)

PM compliance is defined as the percentage of the preventive work scheduled and completed in a set time.  

For example, you might have 60 Work Orders (that are a part of the PM plan) scheduled but 51 completed at the end of the month.

In this case:

PMC= (51/60) x 100 = 85%

This tells you that 85% of all preventive WO’s have been covered for selected month.

The disadvantage of this metric is that it doesn’t tell you if the WO’s have been completed on time. 

That is why you need to invest some additional effort and also track if the Work Orders are actually being finished on time. 

By fat the best way to do that is to use a CMMS as it allows you to quickly create, assign, and track all of your WO’s from one place.



The best way to track if your actions have a positive impact on your maintenance operations is to accurately track metrics that can show you if you are going in the right direction.

Improvements based on your “feeling” can never be as good as relying on hard data.


Bryan Christiansen is the founder and CEO at Limble CMMS. Limble is a modern, easy to use mobile CMMS software that takes the stress and chaos out of maintenance by helping managers organize, automate, and streamline their maintenance operations.

Applications | 15.10.2018

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