Is It 4S or 5S Inside Toyota?

Short answer: Toyota used 4S (Seiri, Seiton, Seiso, Seiketsu) as the company standard for decades. The fifth S — Shitsuke (discipline/sustain) — was added later outside Japan to compensate for cultural differences around daily cleaning habits. The worldwide standard is now 5S, but the original inside Toyota was 4S.

What I Learned in Japan

I learned the Toyota 4S process in Japan, in Japanese: Seiri, Seiton, Seiso, and Seiketsu. Four S was honestly the only term I had ever heard until I moved back to the United States. It was the company standard for decades and it worked just fine.

The Nuance That Gets Lost

There are nuances to the meanings of these words, and one that arguably gets lost in translation is the meaning of “Seiketsu.” You can interpret this to mean maintenance of a cleanly state. Japanese school children grow up practicing cleaning in school every day as part of a daily routine — so there is a built-in culture of cleaning and maintaining a state of cleanliness through daily activities.

That is not the situation in the United States and overseas.

How 5S Happened

To correct for this cultural gap, consultants started tacking on a fifth term — “Shitsuke,” or discipline in Japanese — translating it to mean “sustain.” But this word too has nuances and differences in meaning depending on the person and the situation.

Hiroyuki Hirano’s 5 Pillars of the Visual Workplace (1995) helped popularize the 5S framework worldwide and became one of the most widely used references on the topic.

So most countries outside Japan wound up with the term 5S. I often see a sixth S for safety tacked on as well. I once saw a seventh S for security. You get the point — adding on terms does not make the cycle work.

If you understand the meaning of the 4S terms and invoke them as a daily activity, they are sufficient. If you don’t really understand the terms or the meaning, you end up playing the game of tacking on words and phrases to compensate.

Where Things Stand

The worldwide standard is now 5S, while the original for decades in Toyota was 4S. In many cases today I see the term “4S + 1” used in Japanese to explain the concept, but it depends on the company.