# Converting DPMO & Sigma Level

07/27/2007

How do you covert DPMO to sigma level and sigma level to DPMO?

Al F.

Generally, you would use a table, such as provided in my Six Sigma Demystified book (see below), or you can calculate it directly in Excel using the formula =(NORMSINV(1-$D2))+1.5, where the data in cell D2 is entered as a decimal (for example, 30% error rate = 300,000 DPMO = 0.3 which calculates as 2.02 Sigma Level).

For a given sigma level, the defects per million opportunities (DPMO) is provided, assuming normality and a 1.5 sigma shift. Note that below approximately 3 sigma defects are included from both tails of the normal distribution.

Sigma |
DPMO |

1 |
697672 |

1.1 |
660083 |

1.2 |
621378 |

1.3 |
581815 |

1.4 |
541694 |

1.5 |
501350 |

1.6 |
461140 |

1.7 |
421428 |

1.8 |
382572 |

1.9 |
344915 |

2 |
308770 |

2.1 |
274412 |

2.2 |
242071 |

2.3 |
211928 |

2.4 |
184108 |

2.5 |
158687 |

2.6 |
135687 |

2.7 |
115083 |

2.8 |
96809 |

2.9 |
80762 |

3 |
66811 |

3.1 |
54801 |

3.2 |
44567 |

3.3 |
35931 |

3.4 |
28717 |

3.5 |
22750 |

3.6 |
17865 |

3.7 |
13903 |

3.8 |
10724 |

3.9 |
8198 |

4 |
6210 |

4.1 |
4661 |

4.2 |
3467 |

4.3 |
2555 |

4.4 |
1866 |

4.5 |
1350 |

4.6 |
968 |

4.7 |
687 |

4.8 |
483 |

4.9 |
337 |

5 |
233 |

5.1 |
159 |

5.2 |
108 |

5.3 |
72 |

5.4 |
48 |

5.5 |
32 |

5.6 |
21 |

5.7 |
13 |

5.8 |
9 |

5.9 |
5 |

6 |
3.4 |