Acronym KPI on top of a arrow graph portraying how Key Performance Indicators can help drive maintenance excellence

Key Performance Indicators (KPIs) provide a snapshot of the status of maintenance effectiveness, letting you know where to focus your attention and should be reported, trended, and communicated on a monthly basis throughout the organization. KPIs raise a “red flag” on potential issues as well as highlight key areas of improvement and success.

“When you can measure what you are speaking about and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers your knowledge is unsatisfactory.

— Lord Kelvin, 1884

However, many times, maintenance and facilities departments lack KPI reporting and/or may not know what the KPI world-class maintenance standards are. Look no further, CMMS Data Group is here to help and we’re happy to introduce the 1st KPI, PM (& PdM) to Corrective Ratio, to you.

The question often gets asked: “Are we doing the right number of PMs and PdMs frequently enough?” In a reactive environment, it’s common to see excessive PMs and PdMs being created based on reactive decision making. It’s the “something has failed so let’s make another PM and PdM and do it twice as frequently” approach. The PM (& PdM) to Corrective Ratio is a simple, but effective, KPI to help answer this question.


The PM (& PdM) to Corrective Ratio takes the number of PM and PdM inspections performed during the month and relates it to the number of corrective work orders that were generated from those inspections. The goal for this ratio is 6:1. (For every 6 PMs and PdMs, 1 corrective work order should result.)

  • PM to Corrective Ratio = # of PMs and PdMs Completed / # of Corrective Work Orders Generated

What does the ratio tell me?

High (> 6:1)

If the ratio is greater than 6:1, less than expected corrective work orders are being generated from PM and PdM inspections and this could mean that:

  • PMs are being performed too often creating excess cost and downtime. Additionally, over-PMing can induce failures into the system by excessive intervention.
  • Corrective work isn’t being recorded properly.
  • The content and quality of PM instructions are inadequate or not being properly followed.

Low (< 6:1)

If the ratio is less than 6:1, more corrective work orders are being generated than expected and this could mean that:

  • The interval between PMs may be too large and issues may not be identified soon enough resulting in equipment breakdowns.
  • Not enough PMs (weekly, monthly, quarterly etc.) are in the system.

The PM (& PdM) to Corrective Ratio is kind of a Goldilocks KPI where you want to find that “just right” ratio to ensure your PM program is effectively delivering reliability to the operation without costing too much. This KPI along with others that will be featured in future tips can collectively provide the right information to optimize your maintenance process.

Hope this helps.


To maintenance and reliability success!


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About CMMS Data Group

Founded in 2000 to help organizations achieve maintenance excellence, CMMS Data Group is the market leader in CMMS software and services. Led by the award-winning MVP Plant™ CMMS software and its professional services and technical support, the Company also provides comprehensive reliability engineering services, enabling maintenance and facilities teams to increase customer satisfaction, reliability, capacity, productivity, and profitability.