OEE (Overall Equipment Effectiveness): worked example
| Availability | 90.0% |
|---|---|
| Performance | 95.0% |
| Quality | 99.0% |
| Overall equipment effectiveness | 84.6% |
| Lost to availability, speed and quality | 15.4% |
OEE (Overall Equipment Effectiveness): formula
Common error: Averaging the three percentages. That would give 94.7 percent here and hide about two thirds of the real loss.
Availability is the percentage of scheduled time the equipment ran, after breakdowns, changeovers and waiting. Performance is actual speed compared with the ideal speed, and quality is the share of output that is good the first time. Take them from machine logs, not estimates, and use the same period and scheduled time for all three.
Scheduled time should exclude planned breaks, so the three numbers describe the same window.
OEE (Overall Equipment Effectiveness): changing Availability
| Availability | Overall equipment effectiveness | Lost to availability, speed and quality |
|---|---|---|
| 86.0% | 80.9% | 19.1% |
| 88.0% | 82.8% | 17.2% |
| 90.0% (example) | 84.6% | 15.4% |
| 92.0% | 86.5% | 13.5% |
| 94.0% | 88.4% | 11.6% |
OEE (Overall Equipment Effectiveness): compare input ranges
| Input | Tested from | To | Overall equipment effectiveness: low input | Overall equipment effectiveness: high input | Swing |
|---|---|---|---|---|---|
| Availability | 88.0% | 92.0% | 82.8% | 86.5% | 3.8% (4.4%) |
| Performance | 93.0% | 97.0% | 82.9% | 86.4% | 3.6% (4.2%) |
| Quality | 97.0% | 101.0% | 82.9% | 86.4% | 3.4% (4.0%) |
OEE (Overall Equipment Effectiveness): individual input comparisons
| Input | Value | Overall equipment effectiveness | Lost to availability, speed and quality |
|---|---|---|---|
| Availability | 86.0% | 80.9% | 19.1% |
| 88.0% | 82.8% | 17.2% | |
| 90.0% | 84.6% | 15.4% | |
| 92.0% | 86.5% | 13.5% | |
| 94.0% | 88.4% | 11.6% | |
| Performance | 91.0% | 81.1% | 18.9% |
| 93.0% | 82.9% | 17.1% | |
| 95.0% | 84.6% | 15.4% | |
| 97.0% | 86.4% | 13.6% | |
| 99.0% | 88.2% | 11.8% | |
| Quality | 95.0% | 81.2% | 18.8% |
| 97.0% | 82.9% | 17.1% | |
| 99.0% | 84.6% | 15.4% | |
| 101.0% | 86.4% | 13.6% | |
| 103.0% | 88.1% | 11.9% |
OEE (Overall Equipment Effectiveness): combined input changes
| Availability / Performance | 91.0% | 95.0% | 99.0% |
|---|---|---|---|
| 86.0% | 77.5% | 80.9% | 84.3% |
| 88.0% | 79.3% | 82.8% | 86.2% |
| 90.0% | 81.1% | 84.6% | 88.2% |
| 92.0% | 82.9% | 86.5% | 90.2% |
| 94.0% | 84.7% | 88.4% | 92.1% |
OEE (Overall Equipment Effectiveness): which assumptions move the result?
OEE (Overall Equipment Effectiveness): values and definitions
| Quantity and definition | Value used |
|---|---|
| Availability — Run time as a share of planned time. | 90.0% |
| Performance — Actual speed as a share of ideal speed. | 95.0% |
| Quality — Good units as a share of all units made. | 99.0% |
| Overall equipment effectiveness | 84.6% |
| Lost to availability, speed and quality | 15.4% |
OEE (Overall Equipment Effectiveness): half and double Availability
| Availability | Overall equipment effectiveness |
|---|---|
| 45.0% | 42.3% |
| 90.0% | 84.6% |
| 180.0% | 169.3% |
OEE depends on how ideal speed and scheduled time are defined, so comparisons between plants or companies need common definitions. Improving one factor at the expense of another, such as running faster and making more scrap, does not help. It does not capture whether the equipment is producing what customers want.
Business Finance calculators: Takt Time Calculator, Safety Stock Calculator, Little's Law Calculator, Conversion Rate Calculator, A/B Test Significance Calculator, Overhead Rate Calculator.
Overall equipment effectiveness multiplies three shares: how much of the planned time the machine ran, how fast it ran, and how many good units it made. At 90, 95 and 99 percent, the product is about 84.6 percent, so even three good-looking numbers leave more than a seventh of the potential lost. Multiplying them, not averaging, is the point, since each loss cuts into what is left.
Measure all three from the same period. A speed figure from one shift and a quality figure from another gives an OEE that describes neither.
Use the takt time calculator to set the pace needed to meet demand, and Little's law page for flow through the process. The units of production depreciation page relates usage to cost. Track the six big losses: breakdowns, setups, minor stops, reduced speed, startup rejects and production rejects.
Can the three factors be averaged?
No. The product is 84.645% in the example, while the average is 94.667%.
Does a higher OEE prove the factory is more profitable?
No. OEE measures the defined productive-time relationship, without selling price, demand or production cost. A productive-time ratio and a profit measure have different denominators and inputs.
Higher utilization alone does not establish higher earnings.
What is a good OEE?
Compare availability, performance and quality for a consistently defined process and planned production interval. The cycle-time standard and treatment of downtime materially affect OEE. A universal percentage target can hide different products, production limits or accounting definitions.
What are the three parts of OEE?
Availability, performance and quality. Their product shows how much of the planned production time is truly productive.
How can I raise OEE?
Attack the biggest loss first: reduce downtime with maintenance and faster changeovers, remove minor stops and slow cycles, and cut defects with process control.