Free tools
The working numbers, computed live.
The calculations every practitioner reaches for — free, instant, and right in your browser. Bookmark this page; it works during meetings.
The sigma explorer.
Move your cursor along the curve, then drag the slider to see what each sigma level leaves outside the specification limits.
Inside spec
99.73%
Defects (DPMO)
2,700
In plain terms
Typical for an unimproved process.
Textbook two-sided limits on a centered process, no 1.5σ shift — the classic classroom picture. The DPMO calculator above applies the conventional shifted view used in industry reporting.
DPMO and sigma level
Count your defects, get your sigma — the number the whole methodology is named after.
DPMO
7,400
Yield
99.26%
Sigma level
3.94σ
Short-term sigma including the conventional 1.5σ shift. Zero defects shows 6σ+ — collect more data before celebrating.
Process capability (Cp / Cpk)
How comfortably does your process fit inside its specification limits?
Cp (potential)
1.33
Cpk (actual)
1.20
Marginally capable — acceptable for some processes, worth improving.
Sample size planner
How much data you need before a proportion estimate deserves your trust.
Samples needed
385
For estimating a proportion at worst-case variability (p = 0.5) — the standard conservative planning number.
Takt time
The drumbeat of demand: how often a unit must finish to keep pace with customers.
Takt time
2m 30s
One unit must leave the process this often to exactly meet demand — the heartbeat Lean paces work to.
Beyond the calculators
Learn what these numbers mean — and how to move them.
Every tool on this page is taught in depth in our programs, with the statistics to use them credibly. Start free.
Want the theory behind each tool? The glossary covers every term these calculators use.