DPMO: Defects per Million Opportunities
DPMO is one of a few important Six Sigma metrics that you should understand, appreciate and get comfortable with if you want to be associated with Six Sigma.
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In order to understand DPMO it's best if you first understand both the nomenclature and the minor nuances such as the difference between defect and defective.
Nomenclature
 Defects = D
 Unit = U
 Opportunity to have a defect = O
Defect vs. Defective
In order to properly discuss DPMO we must first explore the differences between "defects" and "defective"
 Defective:

Defective suggests that the value or function of the entire unit or product has been compromised. Defective items will always have at least one defect. Typically however, it takes multiple defects and/or critical defects to cause and item to be defective.
 Defect

A defect is an error, mistake, flaw, fault or some type of imperfection that reduces the value of a product or unit. A single defect may or may not render the product or unit "defective" depending on the specifications of the customer.
 Summary

Defect means that part of a unit is bad, Defective means that the whole unit is bad
Now that you better understand Defects vs. Defective, we must turn to defining "opportunities" so that we can fully understand DPMO.
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Opportunities are the total number of possible defects. Therefore, if a unit has 6 possible defects then each unit produced is equal to 6 defect opportunities. If we produce 100 units then there are 600 defect opportunities.
Defects per Million Opportunities is therefore a simple concept. If you average 4 defects every 100 units (4 defects every 600 opportunities) then your DPMO is (4/600)*1,000,000 or 6667.
The equation is DPMO = (D/(U*O))*1,000,000
You might be wondering now, "what is the reason or significance of 1,000,000"? Well, that feature comes into play when the performance of your process approaches Six Sigma.
When this happens, the number of defects shrinks to virtually nothing....in fact, if you recall from the What is Six Sigma module, it's 3.4 defects per million opportunities.
By using 1,000,000 opportunities as your barometer we have the resolution in our measurement to count defects all the way up to Six Sigma
Below is an image of a DPMOSigma Level Table available as a free download from our store. With this handy "1 pager" you can quickly check your sigma level with a known DPMO or vice versa. So, if you followed the lesson above and you were able to calculate your DPMO, now you can use this free table and you'll know your Sigma Level too!