Work out six sigma level instantly with clear inputs, formula shown and shareable results.
Sigma level converts DPMO into the familiar 1-to-6 scale using the standard long-term approximation with the 1.5-sigma shift built in. Six sigma corresponds to 3.4 DPMO; four sigma, the typical industrial level, allows about 6,210.
Sigma level
Sigma = 0.8406 + sqrt(29.37 - 2.221 x ln(DPMO))
DPMO
DPMO = Defects / (Units x Opportunities) x 1,000,000
It allows for long-term process drift. Without it, six sigma would imply 2 defects per billion rather than the quoted 3.4 per million.
Not always. Moving from four to five sigma is a large investment; justify it against the cost of the defects it removes.