Lean tools

Seven wastes

In French: Les sept gaspillages (muda)

The seven wastes classify everything a process consumes without the customer having asked for it: overproduction, waiting, transport, over-processing, inventory, motion and defects.

What it is

Muda is Japanese for what is useless. The typology in seven categories comes from the Toyota Production System and serves as a reading grid: rather than looking for "improvements", one looks, category by category, for what the process consumes with nothing in return for the customer.

The test is simple, and deliberately severe: would the customer agree to pay for this operation if they saw it? A final inspection, a bin being moved, data being re-keyed do not pass that test — which does not mean they can be removed tomorrow, but that they are candidates.

The seven categories

Overproduction — producing earlier or more than needed. It is the most serious waste because it generates all the others: stock, transport, handling, and defects discovered late.

Waiting — an operator waiting for the machine, a machine waiting for the part, a file waiting for an approval.

Transport — moving material without transforming it.

Over-processing — doing better or more than what is asked: a needlessly tight tolerance, a report nobody reads.

Inventory — work in progress and finished goods, which hide problems as much as they tie up cash.

Motion — the operator’s useless movements, to be distinguished from the transport of material.

Defects — scrap, rework, and all the processing work that goes with them.

An eighth category is commonly added today: the under-use of skills. It is not in the original list, and it is better to say so when teaching it.

The common mistake

Going after motion and waiting because they can be seen, and leaving overproduction alone because it bothers nobody — on the contrary, it reassures. Yet it is overproduction that feeds the rest. A workshop that produces ahead "so as not to stop the machine" manufactures stock, transport and defects discovered too late.

On the shop floor — Financial services

In a back office, the dominant waste was neither transport nor inventory in the physical sense, but waiting: a file spent 92 % of its lead time in a queue, waiting for a signature. The seven categories carry over to services, provided "inventory" is translated as "files waiting".

The other tools illustrated by this trade: banking, insurance and back office.

Frequently asked questions

What are the seven wastes of Lean?

They are usually listed in this order: producing early or in excess, waiting, moving material, doing more than asked, tying up work in progress, multiplying useless motions, and manufacturing non-conforming product. The order is not indifferent — the first feeds almost all the others.

Is there an eighth waste?

The under-use of skills is very often added, to the point of being presented as part of the list. It was not part of it originally, and it is better to make that clear when teaching it: it is a later addition, widely accepted, but an addition.

Do the seven wastes apply to services?

Yes, provided the industrial vocabulary is translated. A file waiting in a queue fulfils exactly the function of shop-floor work in progress; re-keying stands in for handling; a report nobody opens counts as excess work. The grid remains usable; it is the examples that change.