# Six Sigma - Defect Metrics

Before we go ahead, let us define two terms:

• A Six Sigma defect is defined as anything outside of customer specifications.

• A Six Sigma opportunity is the total quantity of chances for a defect.

This chapter provides a list formulae normally used to measure different metrics related to Six Sigma defects.

## Defects Per Unit - DPU

```         Total Number of Defects
DPU =    ------------------------
Total number of Product Units
```

The probability of getting 'r' defects in a sample having a given DPU rate can be predicted with the Poisson Distribution.

## Total Opportunities - TO

```TO = Total number of Product Units x Opportunities
```

## Defects Per Opportunity - DPO

```         Total Number of Defects
DPO =    ------------------------
Total Opportunity
```

## Defects Per Million Opportunities - DPMO

```DPMO =   DPO x 1,000,000
```

Defects Per Million Opportunities or DPMO can be then converted to sigma values using Yield to Sigma Conversion Table given in Six Sigma - Measure Phase.

According to the conversion table −

```6 Sigma = 3.4 DPMO
```

## How to find your Sigma Level

• Clearly define the customer's explicit requirements.
• Count the number of defects that occur.
• Determine the yield-percentage of items without defects.
• Use the conversion chart to determine DPMO and Sigma Level.