Key Points
- Understanding how your yield translates to Sigma Level leads to higher quality products.
- Production should strive for 6 Sigma, 5 Sigma is acceptable.
- The optimal DPMO should be 3.4 defects
- The conversion chart is stable, and readily referenced when applied to your production line.
Quality is paramount no matter what you’re making. Whether it’s a product, service, or some other deliverable, you want to guarantee near-perfection. Determining how often defects arise can be a bit tricky, but you’ll want to use the included Yield to Sigma table in our guide to determine the defects per million opportunities in your production.
Understanding the Chart
The below chart is divided into three columns. If you’re new to figuring out your Defects Per Million Opportunities, or DPMO, it helps to break down some of the nomenclature. Yield % refers to the number of units produced free of defects. This directly correlates with the Sigma, hence Yield to Sigma. The higher the Sigma level, the higher the production quality. You can then determine the DPMO, with 3.4 being the ideal.
Further, the Sigma levels can be broken down as such:
- 6 Sigma: Excellent quality, this should be your target for any project.
- 5 Sigma: Excellent quality, a more achievable target.
- 4 Sigma: Good quality, minimal defects per production, equating to roughly 6 or so per million opportunities.
- 3 Sigma: Average quality, defects are more common.
- 2 Sigma: Poor quality, the process itself needs improvement.
- 1 Sigma: Terrible quality, you’re looking at nearly 700,000 DPMO.
Ideally, this Yield to Sigma conversion table should encourage your team to target the highest possible quality in production. You can also this table to hone in on areas where your organization’s efficiency is lacking. This in turn leads to increases in profitability and customer approval.
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 |
How Does This Apply to Your Deliverables?
Defects in a production line are just a part of life. However, by continually striving for quality and armed with hard data, we can readily address the needs and wants of our customers. Further, having a conversion table like the centerpiece of today’s guide cuts out some of the legwork.
Sigma Levels are intended to improve quality and reduce flaws. These are tried and tested metrics, and you’ll see the results soon enough if you start striving for a 6 Sigma in your production line.
Other Useful Tools for Production
You can take these tools much further with our conversion chart that goes between Sigma Level, Yield, and Cpk. This handy tool is a short read and will help you strive for the best possible quality around. However, that is only part of the quest for near-perfection.
Understanding how to calculate the Sigma Level of your process is vital. Our handy guide is a brisk read, especially if you’re proficient in statistical analysis. Both these tools will have your customers singing your praises in no time.
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. Since the data is normally distributed, the process is stable. Further, the calculations are made using one-tail values of the normal distribution.
