OEE Calculator
Overall equipment effectiveness from availability, performance and quality — and which of the three is costing you most.
OEE multiplies three factors: availability (did the machine run when it should have), performance (did it run at its rated speed) and quality (were the parts good).
How the oee calculator works
OEE multiplies three factors: availability (did the machine run when it should have), performance (did it run at its rated speed) and quality (were the parts good).
Multiplying is what makes it brutal. Three respectable-looking factors of 90% give 72.9%, not 90%. World-class OEE is generally cited as 85%, which needs roughly 90 / 95 / 99 across the three — and most plants measuring honestly for the first time find themselves around 60%.
The number alone is not actionable; the split is. This page names the weakest factor and shows what fixing it would be worth, because effort spent on the wrong one produces very little.
One definitional warning: what counts as planned downtime is where plants disagree. Excluding changeovers from planned production time flatters availability considerably, and two plants using different conventions cannot be compared.
Formula: OEE = availability × performance × quality
Worked examples
| Inputs | OEE | Note |
|---|---|---|
| A shift with 47 minutes lost | 74.5% | about 71% |
| No downtime | 74.5% | availability 100% |
| A quality problem | 60% | quality is the weak factor |
FAQFrequently asked questions
What is OEE?
Overall equipment effectiveness — availability × performance × quality, expressed as a percentage.
What is a good OEE?
85% is the usual world-class benchmark. Most plants measuring honestly for the first time land around 60%.
Why is OEE so much lower than each factor?
Because they multiply. Three factors of 90% give 72.9%.
Does planned downtime count against availability?
Not by the standard definition — but what counts as planned is where plants disagree, and excluding changeovers flatters the number considerably.
Which factor should I fix first?
The weakest, which this page names. Effort on an already-strong factor produces very little.
Where these figures come from
- Nakajima (1988) — Introduction to TPM — the origin of Overall Equipment Effectiveness and its six big losses
- OSHA — the US workplace safety administration
Last checked: September 2026. Definitions follow standard operations-management practice; where plants commonly differ, the page says so.