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 |