Defects per opportunity (DPO) corrects for complexity. DPO = total defects ÷ (units inspected × opportunities per unit). The denominator is the total number of chances the process had to produce a flaw. Because DPO is usually a very small decimal, it is scaled up to defects per million opportunities: DPMO = DPO × 1,000,000. A DPMO of 2,000 reads more easily than a DPO of 0.002 and lets you compare a blister line with a bottling line or an invoice process on the same footing.
The arithmetic is short, but the opportunity count carries all the weight. Doubling the opportunities per unit halves the DPMO without a single improvement on the line. That is why the count must be fixed in advance and tied to real, distinct failure modes that are actually inspected.
Standard Procedure
- 1Multiply units inspected by opportunities per unit to get total opportunities.
- 2Divide total defects by total opportunities to get DPO.
- 3Multiply DPO by 1,000,000 to get DPMO.
- 4State the opportunity definition alongside the DPMO every time it is reported.
Lesson Summary
- ✓DPO and DPMO normalise defect counts by the number of chances, allowing fair comparison across products.
- ✓The opportunity count is the most abused number in the method; document it and keep it constant.