Calculator
Formula used
How to use this calculator
- Enter the number of units inspected in your incoming check.
- Set opportunities per unit to match your CTQs or inspection points.
- Enter total defects, or enable severity breakdown for detailed logging.
- If using weights, choose “Weighted defects” and agree weights internally.
- Press calculate. Use DPMO to compare suppliers and lots fairly.
- Download CSV or PDF to attach results to a supplier report.
Example data table
| Supplier | Lot | Units | Opp/Unit | Defects | DPMO | Notes |
|---|---|---|---|---|---|---|
| Alpha Components | A-2409 | 1,000 | 6 | 14 | 2,333.33 | Stable; monitor cosmetic drift. |
| Beta Plastics | B-2411 | 800 | 4 | 22 | 6,875.00 | Short shot defects increased. |
| Gamma Metals | G-2407 | 500 | 8 | 9 | 2,250.00 | Dimensional checks improved. |
| Delta Fasteners | D-2410 | 2,000 | 3 | 6 | 1,000.00 | Good performance; keep sampling plan. |
| Epsilon Electronics | E-2412 | 600 | 10 | 35 | 5,833.33 | Incoming test failures need containment. |
FAQs
1) What does Incoming DPMO measure?
It estimates defects per million possible defect opportunities found during incoming inspection. It helps compare suppliers and lots even when parts have different numbers of inspection points.
2) How do I choose opportunities per unit?
Use the count of CTQs, inspection checks, or defect chances per unit. Keep it consistent across time. If you change CTQs, note the change so trends remain interpretable.
3) What’s the difference between DPMO and PPM?
PPM here is defects per million units. DPMO is defects per million opportunities, which adjusts for multiple potential defect points per unit. DPMO is better for complex items.
4) Should I use weighted defects?
Only if your team agrees on severity weights and uses them consistently. Weighted results can prioritize high-risk defects, but they are less comparable with teams using different weight rules.
5) Why are there two yield values?
Simple yield uses (1 − DPO). Poisson yield uses e^(−DPU) and estimates the chance a unit has zero defects under a Poisson assumption. Use one method consistently for reporting.
6) How is sigma level calculated here?
The calculator converts DPMO to a Z value using an inverse normal function, then adds a user-selected shift. The shift is commonly set to 1.5 for long-term benchmarking.
7) What if my DPMO is zero?
Zero observed defects can happen with small samples. Treat it as “at least this good” rather than perfect. Increase sample size or track more lots to build confidence.
8) How can I use results for supplier actions?
Trend DPMO by supplier and defect type, then set containment and corrective actions when bands worsen. Combine with audit findings and process changes to confirm improvements.