Muda, Mura, Muri

Muda, Mura and Muri are three terms used together in the Toyota Production System to describe wasteful practices to be eliminated. Muda is any activity that consumes resources without creating value for the customer, Mura is unevenness in an operation, and Muri is overburdening equipment or operators. The three are related, so removing one often removes the others.

Source checked2/2 values · 2026-10-25Methodology

Specification

1 source

Kind	methodology
Origin	Toyota Production System

Study notes

Also called the Three Ms or 3M.
Muda is split into type one muda, which cannot be eliminated immediately, and type two muda, which can be eliminated quickly through kaizen.
A rework operation after a paint booth is given as an example of type one muda, because a fully capable fine-finish paint process is not available.
Multiple movements of products and inventories between steps in fabrication and assembly are given as an example of type two muda, removable in a kaizen workshop by moving equipment and operators into a flowing cell.
Mura is unevenness such as a schedule not driven by end-consumer demand, or an uneven work pace that makes operators hurry and then wait; it is reduced by level scheduling and attention to the pace of work.
Muri is requiring equipment or operators to run at a higher or harder pace, with more force and effort, for longer than equipment designs and workforce management allow.
Worked example: six tons of material must be shipped on a truck rated for three tons; one trip of six tons is muri, two trips of four and two tons are mura and muri, three trips of two tons are muda, and two trips of three tons eliminate all three.
No formula is given in the document.

Safety

Overburdening equipment beyond its rated capacity (muri) leads to breakdowns.