Plotly Supplier Quality Graph
The graph compares historical ppm performance with lot rejection rate so teams can spot whether defect density and shipment failures are rising together.
Enter Supplier Inspection Data
Use the fields below to analyze incoming quality, rejection burden, and supplier risk.
Example Data Table
| Month | Supplier | Lots Received | Lots Rejected | Units Received | Units Rejected | PPM |
|---|---|---|---|---|---|---|
| Aug 2025 | Alpha Components Ltd. | 32 | 2 | 9,400 | 168 | 17,872 |
| Sep 2025 | Alpha Components Ltd. | 28 | 1 | 8,750 | 109 | 12,457 |
| Oct 2025 | Alpha Components Ltd. | 36 | 4 | 11,200 | 344 | 30,714 |
| Nov 2025 | Alpha Components Ltd. | 30 | 2 | 10,100 | 144 | 14,257 |
| Dec 2025 | Alpha Components Ltd. | 40 | 3 | 12,000 | 286 | 23,833 |
This sample shows how receiving teams can compare suppliers over time using lot-level rejection, unit-level defects, and normalized PPM performance.
Formula Used
(Lots Rejected ÷ Lots Received) × 100
(Units Rejected ÷ Units Received) × 100
(Reworkable Units ÷ Units Received) × 100
(Units Rejected ÷ Units Received) × 1,000,000
(Units Rejected × Reject Cost Per Unit) + (Reworkable Units × Rework Cost Per Unit) + Inspection Cost + (Lots Rejected × Lot Penalty Cost)
(Unit Rejection Rate × 0.60) + (Lot Rejection Rate × 0.40)
The weighted score emphasizes defect intensity at the unit level while still accounting for total lot failures that disrupt receiving, inventory, and production planning.
How to Use This Calculator
- Enter the supplier name and review period for the inspection cycle.
- Fill in lots received, lots rejected, total units received, and rejected units.
- Add reworkable quantity plus inspection, rejection, and lot-level cost assumptions.
- Click Calculate Rejection Rate to display the result section above the form.
- Review rejection percentages, PPM, total cost, and supplier risk band.
- Use the CSV and PDF buttons to export the current result for quality reports, vendor reviews, or corrective action meetings.
Why Rejection Matters
Supplier rejection rate is a practical indicator of incoming quality stability. Tracking rejected lots and rejected units together helps teams distinguish shipment failures from recurring part defects. A supplier may pass most lots yet still create hidden loss through sorting, rework, and line interruptions. This calculator turns raw inspection counts into comparable measures for routine supplier reviews.
Percentages and PPM
Unit rejection percentage shows the share of defective material in a delivery, while parts per million standardizes performance across different volumes. In the sample, 286 rejected units from 12,000 received equals 2.38% and about 23,833 ppm. Percentages support internal discussion, while ppm is useful for benchmarking suppliers that ship different quantities or product families.
Lot-Level Signal
Lot rejection rate highlights shipment disruption. If 3 lots are rejected from 40 received, the lot rejection rate is 7.50%. This matters because each rejected lot can trigger containment, replacement requests, and schedule changes. Even when unit defects appear manageable, repeated lot failures often increase receiving effort and production risk faster than teams expect.
Cost of Poor Quality
This calculator links defects to money by combining rejected-unit cost, rework cost, inspection expense, and lot penalties. That structure helps quality and procurement teams move beyond defect counts alone. In supplier meetings, a documented quality cost figure usually creates stronger urgency for corrective action than percentages without financial context.
Composite Supplier Scoring
The composite score weights unit rejection at sixty percent and lot rejection at forty percent. The weighting keeps attention on defect intensity while preserving visibility on shipment failure. Used monthly, the score helps rank suppliers, identify deterioration early, and support decisions on audits, escalation, resourcing, or supplier development priorities.
Monitoring Best Practice
For stronger control, review rejection trends by month, commodity, plant, and defect type. One month may show an isolated event, but a rolling pattern reveals whether corrective action is working. Pair this calculator with delivery performance, complaint response time, and first-pass yield metrics to build a more reliable supplier scorecard. Many teams also set alert thresholds, such as 2% unit rejection or 20,000 ppm, so vendor performance moves from descriptive reporting to disciplined action planning with clear ownership, due dates, and follow-up verification steps.
Frequently Asked Questions
1. What is supplier rejection rate?
It measures the share of incoming lots or units that fail inspection during a review period. Higher values indicate weaker supplier quality and greater operational risk.
2. Should I track lots and units separately?
Yes. Lot rejection shows shipment-level disruption, while unit rejection shows defect density. Using both prevents misleading conclusions when order sizes or batch quality vary.
3. What does ppm mean in this calculator?
PPM means parts per million. It converts rejected units into a normalized defect rate, making supplier comparisons easier across different volumes and product categories.
4. Why include rework cost?
Rework consumes labor, time, and capacity even when material is not fully scrapped. Including it gives a more realistic view of the total quality burden.
5. How often should suppliers be reviewed?
Monthly review is common for active suppliers. High-risk or newly approved vendors may need weekly monitoring until performance stabilizes and corrective actions are verified.
6. Can this calculator support supplier audits?
Yes. The output provides clear evidence for vendor scorecards, corrective action meetings, audit preparation, and sourcing decisions when combined with delivery and response metrics.