The 7 wastes : Transport, Excess inventory, Unnecessary movements, Waiting, Overproduction, Over-processing and Defects.
The 7 wastes
Reading time : 5 min.
7 wastes.
Summary : This article presents the 7 wastes, a concept from the Toyota Production System (TPS), widely used within the framework of Lean management philosophy. This approach aims to identify and eliminate the different wastes in the production and exploitation processes, in order to improve efficiency and productivity.
QuimeO – June 5th, 2025
1. Origin & Author
The 7 wastes approach finds its origin in the Toyota Production System. One of the main motivations behind the development of the TPS was to reduce wastes in the production process to improve efficiency and quality. To reduce those, the 3M were identified as losses: Muda (waste), Muri (excess) and Mura (irregularities).
The 7 wastes concept was later popularised by James P. Womack and Daniel T. Jones in their book The Machine That Changed The World (1990) which helped to make the TPS, and its principles better known. Since then, the 7 Wastes approach appears as one of the pillars of Lean management as it is widely used in numerous industrial sectors to improve operational efficiency and to reduce costs.
2. What are the 7 wastes ?
This methodology, also known as “Muda” in Japanese, aims to identify and eliminate any form of waste in the production processes. A waste is defined as any non-essential, non-productive or any activities which do not contribute to the creation of final value of the product. The objective of this method is to improve efficiency, productivity and rentability. There are 7 categories of waste: Transport, Excess Inventory, Unnecessary Movement, Waiting, Overproduction, Over-processing and Defects. The latter are better known by the acronym TIMWOOD.
2.1 Transport
This waste can be summarised as useless transportation of material or finished products. These transportations can lead to additional costs as well as damage and delays. For example, a delivery driver, who must make several deliveries without having previously planned his journey, may find himself making unnecessary detours which can lead to delays or even the wear of his means of transport. To avoid these different losses, its organisation could plan his optimal journey to avoid traffic jam during rush hours or could even take into consideration the weight of packages to prioritise deliveries, which would prevent any wastes (such as delays, damage, traffic jam…) related to transport.
2.2 Excess inventory
Excess inventory or overstock represents raw materials, finished or semi-finished products, and equipment stock exceeding the company’s storage needs or forecasts. Let’s take the example of a beverage vending machine. If the manager orders a maximal stock during the stock constitution and then, at every replenishment, he fills up with the same quantity of different variety of beverages, he will have an overstock that he could probably not sell. Indeed, the places in the vending machines are limited, analysing the sales to replenish the beverage to suit needs, habits, and consumer preferences will help to avoid an overstock and will also permit to reduce inventory carrying costs.
2.3 Unnecessary movements
Unnecessary movements represent pointless movements that can increase the production time. Not finding tools in a garage and having to search for it, is an unnecessary movement. This movement can be avoided with the implementation of the 5S system which helps to organise and to optimise one’s work environment.
2.4 Waiting
The waiting time for tasks, information, decisions or resources, is considered as a waste. In the project management field, the waiting time related to the validation process can be considered as a waste. This is even more the case with sequential signature, as addresses must sign in a specific order. On the contrary, parallel signatures don’t have to follow a specific order, which allows operators to save time and to accelerate their projects through the validation of the document by all addressees at same time. Using a project management software, as QuimeO, offers the possibility of integrating a system of parallel e–signatures to validate the different stages of a project.
2.5 Overproduction
This waste can be defined as producing more than necessary to meet the demand. Let’s take for example a stainless-steel flask producer. In the case where the company foresees a change like a rise of price in raw materials, exchange rate or supply difficulty, this same company could overproduce to take advantage of current market conditions that seem more favorable than the future ones. If the price at which the company paid to supply its production is actually higher than the future price, the firm would have overproduced with higher production costs, which represent a waste. The producer could use the just-in-time production system, considering the current demand without anticipation. Besides, overproduction leads to every other waste previously mentioned such as waiting, transportation or inventory.
2.6 Over-processing
Over-processing represents all the unnecessary production stages related to value creation such as overengineering, material excess, or overpackaging. For instance, in the automobile industry, a commonly used vehicle has an average lifespan estimated to be around 155,000 miles. Here, over-processing can be represented by an excessive quality over one of the components of the vehicle, like a chassis that can support around 310,000 miles. Adjusting the components’ estimated lifespan to the vehicle one, using mechanical simulation software, allows to avoid this type of waste.
2.7 Defects
It represents errors produced by deficient production management. In the construction industry, not providing the same measuring and tracing tools to all employees can lead to important fabrication defects, implying additional costs to the company. In this way, the organisation could provide the same measuring tools to all employees along with carrying out regular audits to carefully track projects’ progress and to make sure those run smoothly.
However, the 7 wastes list extends to 8 wastes lately. Indeed, the 8th source of waste in Lean would be underutilising employee’s Skills (hence the acronym TIMWOODS). This waste translates into the wrong allocation of tasks to resources, without considering their skills. To resolve that, companies should be careful to not allocate overqualified or underqualified staff to make their skills shine even better!
3. Conclusion
The 7 wastes, inspired by the Toyota Production system and the Lean philosophy, can be used as a powerful model to identify and eliminate the waste sources in the production processes. To solve these wastes in the long term, organisations need to raise awareness among their employees and train the teams to involve them in operations improvement. Employees would be able to evaluate and identify sources of waste more easily to reduce it. This way, organisations can improve their operational efficiency, reduce costs and optimise processes.
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