To calculate overall equipment effectiveness, multiply its three contributing factors: availability, quality and performance. Compile your results. You'll need the summary data for each factor, along with a calculator or computer. Calculating and compiling the resulting data should take about an hour.
- Determine availability and quality
To calculate availability, divide operating time by planned production time. The calculation takes into account losses from factory downtime. To determine quality, divide good pieces by the total pieces produced.
- Assess performance
To determine performance, divide operating time by total pieces produced. Performance is the same as the ideal cycle time, which is the lowest production time that a process can achieve in ideal conditions. It is also known as theoretical cycle time or design cycle time.
- Multiply to find OEE, and compile the data
To determine OEE, multiply availability by quality and by performance. The numbers are expressed as percentages, so multiply them accordingly. On a scientific calculator, use the percent sign with each number. For example, if the result of each factor is 90 percent, multiply as: 90% x 90% x 90% = 72.9%. On a regular calculator without a percent function, multiply as 0.9 x 0.9 x 0.9 = 0.729. Multiply the result by 100 to find the percentage. Compile your data, comparing your OEE rate to the average global rate of 60 percent in manufacturing facilities. An OEE of 85 percent or greater is widely considered to be outstanding.