Enter the total number of defects found in a sample, the sample size, and the number of defect opportunities per item to calculate the sigma level.

## Sigma Level Formula

The following table lists the sigma level on a defects per million basis and a percentage yield.

## Sigma Level Definition

What is sigma level? A sigma level is a term used in both statistics and manufacturing to describe the rate of defects per million opportunities as a function of the number of standard deviations from a mean of a sample. For example, in a standard mean data set of 1 million objects, only 3.4 out of a million would fall within the sixth standard deviation.

## Sigma Level Example Problem

How to calculate sigma level?

1. First, determine the total number of defects in the sample.

For this example, there were 100 defects found in the sample.

2. Next, determine the sample size.

These defects were found in a sample size 5,000.

3. Next, determine the number of opportunities for defects in each item.

There are 10 total possible spots of failure in the object.

4. Next, calculate the DPMO.

Using the formula DPMO = Total defects / (sample size*opportunities for failure per item) * 1,000,000. This yields 2,000 DPMO.

5. Finally, determine the sigma level.

Using the table above, the sigma level is found to be 4 sigmas.