Overall equipment effectiveness is the product of three factors: availability, performance and quality. Availability is running time divided by planned production time. Performance is the output actually achieved against what the ideal cycle time would have produced in that running time. Quality is good units divided by total units. Multiply the three and you have the share of planned production time that produced good product at full rate.
Because the three multiply, OEE falls fast. Three respectable factors of 90% give an OEE of 72.9%, which is why 85% is regarded as world-class for a discrete manufacturing line and 60% is closer to typical. A single headline OEE figure is also nearly useless on its own: 60% could be 95% availability with terrible performance, or good running with heavy breakdowns, and the two demand completely different responses.
The measure decomposes the six big losses. Breakdowns and setup time land in availability; idling, minor stops and reduced speed land in performance; scrap and rework land in quality. On the sample entries availability is 87.1%, performance 904.3% and quality 96.7%, giving an OEE of 761.6%. Note that planned downtime is excluded from the calculation entirely — if it were included the measure would be TEEP rather than OEE.
The formula
Availability- Running time ÷ planned production time
Performance- (Ideal cycle time × total units) ÷ running time
Quality- Good units ÷ total units
Ideal cycle time- The fastest sustainable time per unit
How to use this calculator
- Enter planned production time and the unplanned downtime within it.
- Enter the ideal cycle time per unit for the equipment.
- Enter total units produced and how many were defective.
- The gauge shows OEE; the three component factors are reported separately below.
Worked examples
A shift of 480 planned minutes
62 minutes of downtime leaves 418 running, so availability is 87.1%. 4,200 units at a 0.9 minute ideal cycle would need 3780 minutes, so performance is 904.3%. 4,062 good units of 4,200 is 96.7% quality.
Why the product falls so fast
87.1% × 904.3% × 96.7% = 761.6%. Each factor looks respectable and the result does not. Lifting availability alone to 95% would take OEE to 830.9%; lifting all three to 95% would give 85.7%.
How to read your score
Frequently asked questions
Should planned downtime be included?
No. OEE measures effectiveness during planned production time, so scheduled maintenance, breaks and unscheduled shifts are excluded. Including all calendar time gives TEEP, total effective equipment performance, which is a different and much lower figure.
Why is 85% considered world class?
It is roughly 90% availability × 95% performance × 99.9% quality, which is close to the practical ceiling for a discrete manufacturing line. Continuous processes can and do exceed it.
Can performance exceed 100%?
Only if the ideal cycle time is set too slow, or output is being counted incorrectly. A performance figure above 100% is a signal to re-examine the standard, not a cause for celebration.
Is a single OEE number enough?
No. The same OEE can come from very different loss patterns, and the correct action differs completely. Always report the three factors alongside the product.
OEE reference
| Availability | Performance | Quality | OEE | Assessment |
|---|---|---|---|---|
| 60.0% | 70.0% | 95.0% | 39.9% | poor |
| 75.0% | 80.0% | 97.0% | 58.2% | low |
| 87.1% | 78.8% | 96.7% | 66.4% | typical |
| 90.0% | 90.0% | 98.0% | 79.4% | good |
| 90.0% | 95.0% | 99.9% | 85.4% | world class |
| 95.0% | 95.0% | 99.5% | 89.8% | exceptional |
The three factors multiply, so no single one can rescue the others.
| Availability | 70% performance | 80% performance | 88% performance | 95% performance | 99% performance |
|---|---|---|---|---|---|
| 60% available | 40.7% | 46.6% | 51.2% | 55.3% | 57.6% |
| 75% available | 50.9% | 58.2% | 64.0% | 69.1% | 72.0% |
| 85% available | 57.7% | 66.0% | 72.6% | 78.3% | 81.6% |
| 90% available | 61.1% | 69.8% | 76.8% | 82.9% | 86.4% |
| 95% available | 64.5% | 73.7% | 81.1% | 87.5% | 91.2% |
Quality held at 97% throughout, so only the first two of the six big losses vary.