The Quick Comparison
Lean and Six Sigma attack different problems. Lean eliminates waste to improve speed and flow. Six Sigma reduces variation to improve quality and consistency. Lean Six Sigma combines both.
| Dimension | Lean | Six Sigma | Lean Six Sigma |
|---|---|---|---|
| Focus | Eliminate waste | Reduce variation | Both |
| Origin | Toyota (1950s) | Motorola (1986) | 2000s merger |
| Tools | 5S, VSM, Kanban | DMAIC, SPC, DOE | All of the above |
| Speed | Fast — days to weeks | Slower — weeks to months | Flexible |
| Data needs | Observation-based | Data-intensive | Balanced |
| Best for | Flow, throughput, lead time | Defects, consistency, yield | Complex operations |
When to Use Each
🏭 Use Lean When...
- Processes have obvious waste (waiting, motion, overproduction)
- Lead times are too long
- Inventory is piling up
- You need quick wins to build momentum
📊 Use Six Sigma When...
- Defect rates are high and the root cause is unclear
- Process variation is out of control
- You need statistical proof before making changes
- The problem is complex with many possible causes
A Practical Decision Framework
Can you see the problem by walking the floor? → Start with Lean. Do a gemba walk, identify waste, fix it fast.
Is the problem intermittent and hard to pin down? → Use Six Sigma. Collect data, run analysis, find the hidden root cause.
Is the problem "everything is slow AND unreliable"? → Lean Six Sigma. Use lean to speed up flow, then six sigma to lock in quality.
Interactive Demo
Classify manufacturing problems as Lean or Six Sigma. See which tools apply from each methodology.
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