Sigma Level Calculator

Why this number matters

Sigma is the only operational metric that survives translation between industries. A 4σ invoice process and a 4σ maintenance work order produce the same amount of avoidable rework per million cases. That makes Sigma the one honest comparator across a multi-site, multi-function operation.

The trap: most programmes measure Sigma once, celebrate, and never measure again. Sigma is a posture, not a snapshot. If you are not recalculating quarterly on the same process, you are not running CI — you are running a ceremony.

What to do with your result

• Below 3σ: You have a visibility problem, not a capability problem. The defects are already there — they are just not being counted. Start by defining "defect" for one process and measure for 30 days.
• 3σ to 4σ: The standard improvement path. DMAIC works here. So does standard work + daily huddles + weekly improvement cadence. Expect 12–18 months to move one full Sigma.
• 4σ to 5σ: Tools stop being the bottleneck. Culture becomes the bottleneck. This is where the 5 Shifts matter most — especially the shift from heroes to systems.
• 5σ+: Protect it. Nearly every programme that has hit 5σ then slid back to 3σ within 24 months did so because leadership changed and the cadence stopped.