Understanding MTTR, MTBF, MTTF Failure Metrics

kpis reporting mttr, mtbf, mttfKeeping your assets and equipment running at peak performance is critical to any organization.  In today’s world, asset and equipment breakdowns and failures still occur.  It is essential for companies to have a process in place to track all of their assets and equipment that are prone to failures in order to maximize uptime and keep disruptions at a minimum.

With the proper management of failures, you can reduce the negative impact on your organization. To help you manage these failures, there are a number of important metrics that have been put in place to help you monitor these failures. 

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Some of the industry’s most commonly tracked metrics are MTTR (mean time to repair), MTBF (mean time before failure), and MTTF (mean time to failure).  We’ll discuss what each of those acronyms means and how you can use them to improve your operations.

Mean Time To Repair (MTTR)

Mean Time To Repair (MTTR) is a Key Performance Indicator (KPI) that represents the average time required to troubleshoot and repair failed equipment and return it to normal operating conditions. MTTR gives organizations a more accurate analysis of how well their teams are responding to repairs and equipment problems.

Taking too long to repair an asset drives up the costs, due to downtime until the new part arrives and the possible window of time required to make the repair.  To improve MTTR, many companies purchase spare products so that a replacement can be installed quickly. Generally, customers will inquire about the turn-around time of repairing a product, which affects MTTR.

Calculating MTTR

  • Total time spent on unplanned maintenance for an asset.
  • Divide that number by the number of failures that occurred with that equipment over a defined period of time.


  • A generator has broken down 10 times during the years.
  • You spent 100 hours to repair the generator.
  • The MTTR is 10.
  • You need to determine what MTTR value is acceptable for your organization.

Value of MTTR

  • Viewing historic records to make better decisions on when to repair or replace an asset.
  • Gives a snapshot of how quickly the maintenance team responds to failed assets or equipment.
  • Gives you a look into how effective and efficient your preventive maintenance program is performing.

Improving MTTR

  • Keep accurate historic records of repairs and time spent on repairs.
  • Document frequently used parts that are needed for repairs.
  • Ensure that inventory is well stocked.
  • Evaluate the knowledge of the technical staff to determine if additional training or certification is required.

Mean Time Between Failures (MTBF)

Mean Time Between Failures (MTBF) is a KPI that measures equipment reliability and the amount of time that elapses between one failure and the next. These metrics provide detailed and in-depth information on the status of equipment and assets. This KPI helps organizations optimize preventive maintenance schedules to help avoid unexpected failures and unnecessary maintenance. This will let you know the expected life span of an asset.  MTBF is commonly used for repairable items.

Calculating MTBF

MTBF Mean Time Between Failure
  • Identify the total number of operational hours for a specific asset over a defined timeframe.
  • Divide that number by the number of failures that happened during that timeframe.
  • A low MTBF can be contributed to either an operator error or past repairs that were not satisfactorily made. 


  • A piece of equipment has been fully operational for 10,000 hours over a period of one year.
  • The equipment broke down 10 times during that timeframe.
  • The MTBF for this piece of equipment would be 1,000 hours.

 Value of MTBF

  • Identify previous issues and repairs.
  • Identify issues and repair timeframes so that you can properly schedule preventive maintenance before the failure.
  • Improve product quality and reliability.

 Improving MTBF

  • Improve preventive maintenance processes.
  • Do a root cause analysis and get an understanding of why it failed.
  • Look at options, maybe the replacement part needs to be a higher-quality or a different brand.
  • Having a more thorough understanding of your asset and making changes can greatly improve MTBF.

Mean Time To Failures (MTTF)

Mean Time To Failures (MTTF) is a KPI that measures the reliability for non-repairable equipment. It represents the length of time that an asset is expected to last in operation until it fails.  Unlike MTBF which is used for repairable items, MTTF is used when fixing an asset isn’t an option.

Calculating MTTF

MTTF Mean Time To Failures
  • Take the total number of operational hours and divide that by the number of assets you’re monitoring.


  • You have four circulating pumps.
  • First circulating pump fails after ten hours.
  • Second circulating pump fails after twelve hours.
  • Third circulating pump fails after six hours.
  • Fourth circulating pump fails after eight hours.
  • Total uptime of 36 hours.
  • Divide the total uptime of 36 hours by the number of circulating pumps (4), which equals nine hours.
  • The final calculation is the average lifespan of that particular type and model circulating pump.
  • The conclusion is that this specific make and model of circulating pumps will need to be replaced on an average of every nine hours.

Value of MTTF

  • Shows the reliability of the parts, brand, and model pertaining to an asset or piece of equipment.

 Improving MTTF

  • The best way to improve MTTF is to keep your assets and equipment in good working order.
  • Have a good preventive maintenance plan in place.

Final Thoughts

The gathering and analysis of metrics is critical information that is essential for improving operations. Having an understanding of the calculations and failure metrics provides organizations with a better insight into potential asset or equipment failures.  Having the right tools such as eWorkOrders CMMS, gives users the ability to quickly and easily log and keep track of all the pertinent data and labor time from anywhere.  Our extensive reporting and dashboard features give organizations an instant view of how their maintenance operation is performing.

eWorkOrders CMMS provides organizations with easy to use tools that will help you manage your maintenance operations more efficiently.

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