Turn raw errors into actionable engineering quality metrics. Compare modes, rates, and confidence in seconds. Export clean summaries to share, review, and improve today.
| Date | Units | Errors | Opps/Unit | Rate per 1,000 | Notes |
|---|---|---|---|---|---|
| 2026-02-10 | 1200 | 6 | 10 | 5.0 | Startup calibration drift corrected. |
| 2026-02-11 | 1350 | 4 | 10 | 3.0 | New fixture reduced mechanical variance. |
| 2026-02-12 | 1280 | 7 | 10 | 5.5 | Supplier batch change increased solder voids. |
| 2026-02-13 | 1420 | 3 | 10 | 2.1 | Added inline inspection step. |
| 2026-02-14 | 1500 | 5 | 10 | 3.3 | Reworked station training improved consistency. |
Error rate converts defect counts into a comparable indicator across lines, shifts, or firmware revisions. Normalization per 1,000 or per 1,000,000 removes scale bias, so a 6‑error day at 1,200 units can be compared to a 12‑error day at 2,500 units. Track both the raw count and the normalized rate to prevent misleading improvements driven only by volume changes. Segment by station or supplier lot to expose hidden variation early.
Not all errors carry equal impact. Weighting multiplies each category by a severity factor, producing a weighted rate that aligns with safety, warranty cost, or downtime. A minor cosmetic scratch might use 1.0, while a field‑return root cause could be 3.0. When the weighted rate falls faster than the unweighted rate, teams are likely eliminating the most expensive failure modes first. Review weights quarterly so they match current customer risk.
In multi‑step assemblies, each unit contains multiple opportunities for failure. Entering opportunities per unit enables DPO and DPMO, common in Six Sigma reporting. For example, 5,000 units with 12 opportunities each yields 60,000 opportunities. If 50 errors occur, DPO becomes 0.000833 and DPMO becomes 833. These metrics help compare products with different complexity. Keep the opportunity definition stable to preserve year‑over‑year comparability.
Point estimates can swing when sample sizes are small. The calculator reports Wilson confidence intervals for the underlying proportion, which behave well even at low error counts. Use wider intervals as a signal to collect more data before escalating. When two time windows overlap heavily in their intervals, treat changes cautiously and validate with additional runs or controlled experiments. Combine bounds with control limits when building SPC charts.
Use the results summary during daily standups and post‑mortems. Pair the errors per hour metric with staffing levels to detect process strain. Export CSV for trend dashboards and PDF for audit packets. For best outcomes, log corrective actions beside each period and re‑calculate after changes, ensuring the reduction is sustained rather than a temporary shift in detection. Assign an owner per category and close the loop with verification sampling and preventive actions.
Use per 1,000 for shop-floor tracking and per 1,000,000 for very low defect environments. Keep the same factor across reports so stakeholders can compare periods consistently.
Start with 1.0 for minor, 2.0 for major, and 3.0 for critical issues. Align weights to safety, warranty exposure, and downtime cost, then review them after major product or process changes.
An interval shows the likely range of the true error proportion given your sample size. Small samples produce wider ranges, helping you avoid overreacting to random variation in daily counts.
Use them when each unit has multiple independent opportunities for failure, such as connectors, joints, or checks. DPMO helps compare processes with different complexity using a consistent scale.
Yes. Select the Testing mode and enter total test cases and failures. The tool returns failure rate, pass rate, and failures per selected normalization, plus confidence bounds for the failure proportion.
After submitting, use Download CSV for dashboards and Download PDF for audits or emails. The exports include the summary table and, in defect mode, the category breakdown.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.