iSixSigma

Yield to Sigma Conversion Table

Yield % Sigma Defects Per Million
Opportunities
99.9997 6.00 3.4
99.9995 5.92 5
99.9992 5.81 8
99.9990 5.76 10
99.9980 5.61 20
99.9970 5.51 30
99.9960 5.44 40
99.9930 5.31 70
99.9900 5.22 100
99.9850 5.12 150
99.9770 5.00 230
99.9670 4.91 330
99.9520 4.80 480
99.9320 4.70 680
99.9040 4.60 960
99.8650 4.50 1350
99.8140 4.40 1860
99.7450 4.30 2550
99.6540 4.20 3460
99.5340 4.10 4660
99.3790 4.00 6210
99.1810 3.90 8190
98.9300 3.80 10700
98.6100 3.70 13900
98.2200 3.60 17800
97.7300 3.50 22700
97.1300 3.40 28700
96.4100 3.30 35900
95.5400 3.20 44600
94.5200 3.10 54800
93.3200 3.00 66800
91.9200 2.90 80800
90.3200 2.80 96800
88.5000 2.70 115000
86.5000 2.60 135000
84.2000 2.50 158000
81.6000 2.40 184000
78.8000 2.30 212000
75.8000 2.20 242000
72.6000 2.10 274000
69.2000 2.00 308000
65.6000 1.90 344000
61.8000 1.80 382000
58.0000 1.70 420000
54.0000 1.60 460000
50.0000 1.50 500000
46.0000 1.40 540000
43.0000 1.32 570000
39.0000 1.22 610000
35.0000 1.11 650000
31.0000 1.00 690000
28.0000 0.92 720000
25.0000 0.83 750000
22.0000 0.73 780000
19.0000 0.62 810000
16.0000 0.51 840000
14.0000 0.42 860000
12.0000 0.33 880000
10.0000 0.22 900000
8.0000 0.09 920000

Assumptions
No analysis would be complete without properly noting the assumptions made. In the above table, we have assumed that the standard sigma shift of 1.5 is appropriate (the process sigma calculator allows you to specify another value), the data is normally distributed, and the process is stable. In addition, the calculations are made with using one-tail values of the normal distribution.

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