PPM calcuation

We must go into the definition of a defect versus a defective unit.
The definition of opportunity I utilize is a measurable chance for a defect to occur.
a defect is any event that does not meet the customer specification.
A defective is a unit with one or more defects.
 
Based on your write up I inferred that you may have one defect with multiple ways for that defect to occur (i.e. a poor weld can be catagorized in many ways but it is still just one defect).
 
So without knowing more about your situation I hope this helps.

Amit,
Note that I agree with RR Kunes that there is a difference between a defective unit and the number of defects per unit. With that said, here’s how I would tackle the situation.
From the data you provided:
Total Units: 5,600
Opportunities Per Unit: 30 (not sure why you then stated 37 later in your original post — I’m going to stick with 30)
Total Defects: 1,331 (note: not using the defectives/defective units, but the total number of defects which you are trying to eliminate)
Calculator: 3.912 Process Sigma
Anyone else agree?

Original message stated that numbers were from one day’s production, so this is short-term data.
DPO = 1331/168,000 = .0079.  Z = 2.41 short-term.  Subtract 1.5 to get long-term, you end up with ZLT = 0.91.
The calculator automatically puts the shift in – put in 0.0 for shift, you will get the same answer

Amit,This is the way I see it using the sigma calculator on this site.Sigma CalculatorEnter your process opportunities and defects and press the “Calculate” button.Switch To: Basic ModeUnitsOpportunities/UnitDefectsSigma ShiftCalculation Results DPUDPMODefects (%)Yield (%)Process Sigma© iSixSigma 2000-2002