Calculation of OEE- Overall Equipment Efficiency

Calculation of OEE- Overall Equipment Efficiency

OEE is an important metric, as it ties-in, well with the objectives of TPM program, which aims at having,
Zero-breakdowns and
Zero-stops in the production process.

The three components of overall equipment effectiveness metric are:

  1. Availability
  2. Performance
  3. Quality

The definitions of each of above components are as below,

  1. Availability – is a measure of the time in percentage that a process is available for productive work. Availability matrix is important to measure and ensure that there are no break-downs and downtime beyond already planned downtime.
  2. Performance – Is measures of how well a process performed against the set targets and mainly base on the speed of production
  3. Quality – is a measure of good parts percentage, against total parts produced. This has relation with defective part produced from the process, rework.

OEE = Availability X PerformanceX Quality

OEE = Availability X PerformanceX Quality


MTBF and MTTR are important Key Performance Indicators to monitor the process performance and related to availability of the equipment.

Let us examine the MTBF and MTTR and how they are useful in improving the effectiveness and efficiency of the equipment.

MTBF – Mean Time between Failures

This is ratio of Total time of operation without delay to Number of Failures or Break downs.

MTTR – Mean Time to Repair

This is ratio of total down time or time required for repair of breakdown to Number of Failures or Break downs.


If a machine planned to operate for 11 hrs, whereas there is 5 nos of breakdown, total time consume in breakdown is 1 hr.

Calculate MTBF and MTTR

MTBF = (11-1)/5 = 10/5 = 2 hrs

MTTR = 1/5 = 1/5 = 0.2 hrs

The relation between MTBF MTTR and Availability is as below,

Availability %= MTBF/(MTBF+MTTR)

Availability %= = 2/ (2+0.2) = 90.91%