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Six Sigma Level Calculator

Work out six sigma level instantly with clear inputs, formula shown and shareable results.

About Six Sigma Level Calculator

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.

Formulas

Sigma level

Sigma = 0.8406 + sqrt(29.37 - 2.221 x ln(DPMO))

DPMO

DPMO = Defects / (Units x Opportunities) x 1,000,000

Worked example

With the default values below, Six Sigma Level Calculator returns Process sigma level of 4.26. Change any input above and every figure here is recalculated in your browser.

Inputs used

Defects observed
34
Units produced
2,000
Opportunities per unit
6

Results

Process sigma level
4.26
DPMO
2,833
Process yield
99.7167%
Rating
Industry average

Step by step

  1. 1Values used
  2. 2Sigma level
  3. 3DPMO
  4. 4Process sigma level= 4.26
  5. 5DPMO= 2,833
  6. 6Process yield= 99.7167
  7. 7Rating= Industry average

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • This is an estimate for general information and not professional financial, tax or legal advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why the 1.5-sigma shift?

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.

Is a higher sigma always worth it?

Not always. Moving from four to five sigma is a large investment; justify it against the cost of the defects it removes.

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