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"Who defined the seven wastes of lean?"
Who Defined the Seven Wastes of Lean?
Short answer: Taiichi Ohno is credited with defining the seven wastes (七つのムダ), and that attribution is fair — he put the framework in place. But Ohno did not invent the categories from scratch. He assembled them from existing Industrial Engineering sources that were already in use at Toyota. Five of the seven wastes for example map to standard ASME flow process chart symbols standardized in 1947. The 7 waste framework came together in the 1960s as a way to give shopfloor supervisors and employees a simple, unified vocabulary for non-value-added activity.
Where did the idea of “waste elimination” come from?
The phrase “elimination of waste” (ムダの排除) at Toyota has roots older than the seven-waste framework itself. Training Within Industry (TWI) — the American wartime training program — entered Toyota in 1951. TWI’s Job Methods (JM) course, taught at Toyota around 1953, used the phrase “elimination of unnecessary details” as its central concept. Toyota converted this into its own vocabulary: elimination of waste.
JM also contributed the ECRS framework — Eliminate, Combine, Rearrange, Simplify — a structured approach to improving work methods. This logic persisted at Toyota long after the formal JM program ended. Isao Kato later reincorporated ECRS principles into Toyota’s internal Kaizen Training Course around 1967.
But Ohno found TWI’s Job Methods course materials lacking. It had no time study component or connection to other adjacent concepts by design. That was an explicit decision to the keep the materials simple in nature and easy to roll out during WWII. However it also left a gap that made it insufficient for standardized work and just-in-time production. It did not address Ohno’s biggest concern about the waste of over-production for example. He stopped the formal JM program after roughly two years and instructed the training and education department to find something better to augment the material.
What role did industrial engineering play?
In 1955, Shigeo Shingo began teaching what were called the P-courses at Toyota. P simply stood for Productivity. These were based entirely on Industrial Engineering concepts: process analysis, operational analysis, time study, and motion study. Shingo’s courses filled most of the gap Ohno had identified — they brought the analytical rigor of IE to the shopfloor in a structured teaching format.
This is significant because it means IE methodology — including process analysis with its standard symbols — was being formally taught inside Toyota from the mid-1950s onward. The IE framework was not something Toyota discovered later. It was part of the operating environment in which the seven wastes took shape.
How did Ohno assemble the seven wastes?
Independent of both TWI and Shingo’s courses, Industrial Engineering had long used a set of standard symbols for types of process analysis. These trace back to Frank and Lillian Gilbreth’s work in the 1920s–1930s and were formalized by the American Society of Mechanical Engineers (ASME) in 1947. The five ASME flow process chart symbols classify all activities:
| ASME Symbol | Activity | Toyota Waste |
|---|---|---|
| ○ | Operation | Processing waste (加工そのもののムダ) |
| ⇒ | Transportation | Transportation waste (運搬のムダ) |
| □ | Inspection | Defects (不良をつくるムダ) |
| D | Delay | Waiting waste (手待ちのムダ) |
| ▽ | Storage | Inventory waste (在庫のムダ) |
IE professionals around the world were using these symbols independently. They were useful analytical categories, but there was no simple framework that unified them in a way shopfloor employees could grasp. This framework also did not address Ohno’s specific concern of over-production. He also felt that Operation should be split to address human centric forms of waste which were important for standardized work and process specific wastes that were more engineering related.
To reconcile the situation and give employees a single framework, Ohno at one point simply issued a dictum: there are seven wastes. The logic of the assembly:
- Overproduction came first — the most important waste because it generates so many others. This was Toyota’s own emphasis, not an IE category.
- Five wastes mapped to the five ASME symbols — waiting, transportation, processing, inventory, and defects. These were already well understood from IE training.
- Motion filled a gap. Time study and motion study were core IE disciplines taught in Shingo’s P-courses, but the ASME process chart symbols tracked what happened to the object, not the worker. Toyota drew a sharp distinction between a worker moving (動く) and a worker working (働く). Motion waste captured this — unnecessary movement by the worker that does not advance the process.
One plus five plus one equals seven. It is not a perfect framework and it has some holes in it. But it solved the problem that Ohno was chiefly concerned about at that time.
Why are there only seven wastes?
No. The framework was never MECE — mutually exclusive, collectively exhaustive — and was never intended to be. It was meant to give shopfloor employees and supervisors a simple way to see and categorize waste across man, machine, materials, and method.
Consider what the seven wastes do not cover:
- Energy waste (compressed air, electricity, heat loss)
- Auxiliary material waste (coolant, oils, consumables)
- Safety incidents
- Management overhead
- Measurement and metrics activity
- Environmental wastes
If you wanted an exhaustive taxonomy of everything that adds cost without adding value, the list would be far longer than seven. That was not the point. The framework needed to be simple enough for a production worker to carry in their head and apply at the gemba. Seven categories covering the most visible, most actionable forms of physical waste on the shopfloor — that was the design intent.
The framework has stood for decades not because it is perfect but because it is useful. It gives people a lens. The fact that it does not capture everything is a feature, not a flaw.
What about the “eighth waste”?
Some Western lean authors have attempted to add their wisdom by adding “unused human potential” or “underutilized talent” as an eighth waste. I think the point misses the mark. As indicated above there are many things lacking in this framework. In Toyota today there are still just 7 wastes. Humans are the center of the system. Respect for people and their skills is covered under other elements of TPS. Tacking on an 8th waste does not really accomplish much in my opinion. The seven wastes are grounded in observable, measurable physical waste — things you can see, time, and count on the production floor. Adding abstract organizational concepts changes the nature of the framework entirely. If underutilized intellect counts as waste, why not wasted energy, wasted metrics, or environmental wastes, etc? Why not safety incidents or poor operational strategy? There is no logical stopping point, and the simplicity that makes the framework useful is lost.
See also: What Are the Seven Wastes in the Toyota Production System?, What Is the Difference Between Muda, Mura, and Muri?, What Is Overproduction Waste?, What Is Standardized Work?.