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How to convert DPMO into Sigma Level

Sigma ShiftWe can easily calculate the DPMO but then how does it get converted to process Sigma level?  Confusing?  Below table illustrates the corresponding sigma level for different DPMO values.  Don’t want to use this table and have excel do the work for you?  Yes, you can have excel as your assistant and help you derive the sigma value using below formula:

=(NORMSINV(1-$B2))+1.5, where the data in cell B2 is entered as a decimal (for example, B2 value of 20% defects calculates as 2.34 Sigma Level, 30% is 2.02 sigma value, 40% is 1.75).  Eliminate the 1.5 from calculation and you will have current Z value of the process.

Here is the table that provides the numbers for each sigma level but for accurate results to the last decimal level, use excel:

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

 


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