Overall Equipment Effectiveness

Calculating OEE

OEE measures how much planned production time produces acceptable parts at the ideal rate. Availability is run time divided by planned time. Performance compares ideal time for the total count with actual run time. Quality is the fraction accepted on the first pass.

Example and scope

With 480 planned minutes, one ideal second per piece and 22800 good pieces, OEE is 79.1667 percent. Exclude breaks with no scheduled production before entering planned time. Include changeovers in stop time. This calculation uses one product and one ideal cycle time. Evaluate different products in separate periods.

Reading the losses separately

Check that time records and piece counts cover exactly the same period. Planned time is the period when production is expected, rather than all elapsed calendar time. Choose an ideal time for one piece of the same product. If a cycle produces several pieces, confusing cycle time with time per piece will overstate performance.

For example, take 60 planned minutes, 12 minutes of stops, an ideal time of 3 seconds, 800 total pieces and 720 good pieces on the first pass. Run time is 48 minutes, or 2880 seconds. Availability is 48/60 = 0.8. Ideal production time is 3 × 800 = 2400 seconds, so performance is 2400/2880 ≈ 0.833333. Quality is 720/800 = 0.9. Multiplying these ratios gives OEE of 60 percent.

Check the result using 3 × 720 / 3600 = 0.6. The shortcut checks the total but does not reveal which loss dominates. Reducing stops, reducing slow running and improving first pass quality require different actions. Keep the definition of ideal time consistent when comparing periods. The tool rejects inputs that give performance above 100 percent. If this warning appears, check time units, the piece counter and ideal time. This calculation supplies no industry target or acceptance threshold.