What Is OEE?
OEE is the single most important metric for measuring how effectively manufacturing equipment is being used. It combines three factors — Availability, Performance, and Quality — into one percentage that tells you how much of your planned production time is actually producing good parts.
The Three Factors
Availability
Run Time ÷ Planned Production Time. Measures unplanned downtime losses: breakdowns, changeovers, material shortages, unplanned stoppages. If your shift is 480 minutes and you lost 60 minutes to downtime, availability is 87.5%.
Performance
(Ideal Cycle Time × Total Count) ÷ Run Time. Measures speed losses: running below rated speed, small stops, jams, idling. If your machine should produce 60 parts/hour but is only producing 50, performance is 83.3%.
Quality
Good Count ÷ Total Count. Measures defect losses: scrap, rework, startup rejects. If you produced 950 good parts out of 1,000 total, quality is 95%. See first pass yield for a related metric.
The page's own worked examples, on one axis of shift minutes. Availability 87.5%: a 480-minute shift losing 60 minutes to unplanned downtime, leaving 420. Performance 83.3%: a machine rated at 60 parts an hour running at 50, leaving 350. Quality 95%: 950 good parts of 1,000, leaving 332.5 — an OEE of 69.3%. Note that quality is the strongest of the three factors and still costs 17.5 minutes, because by the time it applies there are only 350 minutes left for it to take from. This is the same mechanism as the page's 90% × 90% × 90% = 72.9%. World-class 85% would be 408 minutes, so the gap is 75.5 minutes of every shift — and it is spread across all three factors, not sitting in one.
OEE Benchmarks
| OEE Score | Rating | What It Means |
|---|---|---|
| Below 40% | Crisis | Significant opportunities in all three factors. Common for plants starting to measure OEE for the first time. |
| 40-60% | Low | Typical for plants with reactive maintenance and no standard work. Large improvement potential. |
| 60-75% | Average | Where most plants actually operate. Indicates room for focused improvement. |
| 75-85% | Good | Well-run operations with active TPM and CI programs. |
| 85%+ | World Class | Benchmark level. Requires sustained TPM, standard work, and continuous improvement culture. |
The OEE Multiplication Trap
Because OEE multiplies three percentages, even small losses compound dramatically. Availability 90% × Performance 90% × Quality 90% = OEE 72.9%, not 90%. This is why world-class OEE at 85% requires each factor to be around 95%+.
The Six Big Losses
Every minute of lost OEE falls into one of six categories. Identifying which losses are biggest tells you where to focus improvement efforts:
| Loss | OEE Factor | Example | Countermeasure |
|---|---|---|---|
| Equipment Failure | Availability | Breakdowns, mechanical failures | Autonomous + planned maintenance |
| Setup / Adjustment | Availability | Changeovers, warmup time | SMED |
| Idling / Minor Stops | Performance | Jams, sensor trips, blocked flow | Focused improvement, poka-yoke |
| Reduced Speed | Performance | Wear, operator caution, wrong settings | Restore to design conditions, standard work |
| Startup Rejects | Quality | Scrap during first articles, warmup | Standardized startup procedures |
| Production Rejects | Quality | In-process defects, rework | Error-proofing, Six Sigma |
How to Improve OEE
🎯 Key Takeaway
OEE is not a target to game — it is a lens that reveals where your hidden factory is. The gap between your current OEE and 100% represents lost capacity you already own. Recovering that capacity through focused improvement is almost always cheaper than buying new equipment. Start measuring today with the free OEE calculator.
OEE Simulator
Drag the sliders to see how Availability, Performance, and Quality multiply together. Notice how small losses in each factor compound into big OEE losses.
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