ISO 22400-2 OEE definitions, and our variant, disclosed.
A reference document. The standard's time model and three factors, the terms MachineWise uses, and precisely where our internal variant differs and what that costs.
This is a reference page. It sets out the OEE-related definitions given in ISO 22400-2 — the international standard for manufacturing operations management key performance indicators — in the terms the standard uses, and then discloses the variant MachineWise computes internally and where it differs.
It exists so that anyone quoting a MachineWise figure can establish precisely what was measured, and so that an auditor, a consultant or a customer can check our definitions rather than take them on trust. It is deliberately written as documentation rather than as an argument.
ISO 22400 is published in parts. Part 2 defines key performance indicators for manufacturing operations management, including the elements from which OEE is constructed. It is an international standard published by ISO; this page describes and applies its definitions and does not reproduce its text. Organisations requiring the standard for compliance purposes should purchase it from ISO or their national standards body.
A point worth stating clearly: OEE itself predates the standard by decades and is used widely in forms that differ from it. ISO 22400-2 matters because it gives a single reference against which two organisations can establish whether they are measuring the same thing — which, in practice, they frequently are not.
Everything downstream depends on which time base is used.
The second box is where most cross-plant disagreement originates. Two plants reporting OEE against different definitions of planned production time — one excluding planned maintenance and breaks, another including them — will produce numbers that differ by many points while both being internally correct. Always establish the time base before comparing.
| Factor | ISO 22400-2 formulation | In plain terms |
|---|---|---|
| Availability | Actual production time ÷ planned production time | Of the time you intended to produce, how much did the equipment actually produce |
| Effectiveness | (Produced quantity × ideal cycle time) ÷ actual production time | While producing, how close to the theoretical best rate did it run |
| Quality ratio | Good quantity ÷ produced quantity | Of what was produced, how much was acceptable |
| OEE | Availability × Effectiveness × Quality ratio | The product of the three |
Note the term Effectiveness. Common usage says "Performance"; the standard's terminology is worth using when precision matters, because the two are sometimes defined differently in commercial software.
| Factor | ISO 22400-2 — the standard | MachineWise variant — internal only |
|---|---|---|
| Availability | Actual production time ÷ planned production time | Machine on-time ÷ reporting time |
| Performance / Effectiveness | (Produced quantity × ideal cycle time) ÷ actual production time | Productive time ÷ machine on-time — a time-in-cut proxy |
| Quality | Good quantity ÷ produced quantity | Identical to ISO |
| Needs a maintained standard? | Yes — an ideal cycle time per part | No |
| Comparable to published benchmarks? | Yes | No — treat as your own baseline |
Why it exists. The ISO Effectiveness calculation requires a maintained ideal cycle time for every part. On an Indian job-shop floor running fifty part numbers a month, that standard is frequently absent, stale or disputed — and an OEE that cannot be computed until standards are maintained is an OEE that never gets computed at all.
What it substitutes. The variant replaces the speed question with a time-in-cut question: of the time the machine was powered, how much involved productive work. That is directly observable and requires no agreed standard, which makes it available from day one and difficult to game.
What it costs. The variant cannot detect a machine running slowly. A machine cutting continuously at half its rated speed scores well on the variant's Performance and poorly on ISO Effectiveness. This is a real limitation, not a nuance.
How it should be used. Internally, as a baseline to improve against. Never as a figure compared to published benchmarks, and never quoted externally without saying which definition produced it. Where both are available, read them together — the gap between them is itself informative, as it separates a not-running problem from a running-slowly problem.
| Term | Definition as used by MachineWise |
|---|---|
| Reporting time | The period over which the figure is computed — shift, day or week — less known breaks and allowed downtime |
| Machine on-time | Time the machine was powered and available within the reporting time |
| Productive time | Time within machine on-time in which productive work was occurring |
| Parts produced | Total components completed, including those later rejected |
| Approved parts | Components accepted after inspection |
| Planned production time | Used where an ISO-basis figure is computed: scheduled production time less planned stoppages |
| Ideal cycle time | The fastest rate at which the machine has demonstrably produced that part — not the quoted rate, and not the average |
These definitions are applied identically across every MachineWise deployment, every page on this site, and the forthcoming benchmark report. Where a figure appears without a stated basis, it is the ISO basis.
State the definition alongside the number
One sentence — 'computed to ISO 22400-2' or 'internal time-in-cut variant' — prevents nearly every downstream dispute.
State the time base
Whether planned production time excludes breaks, planned maintenance and unscheduled shifts. This single fact moves OEE by many points.
Never compare across definitions
An ISO figure from one plant and a variant figure from another are not comparable, and presenting them side by side in a group review is actively misleading.
Publish the split, not just the product
Availability, Effectiveness and Quality separately. The product alone conceals which of three unrelated problems you have.
For the arithmetic applied step by step, see how to calculate OEE. For what the widely quoted world-class figure actually rests on, see world-class OEE. For the input that most often invalidates an ISO Effectiveness figure, see ideal cycle time explained. Both definitions are computed side by side, with your own numbers, in the OEE calculator.