What Is First Pass Yield?
First Pass Yield (FPY) measures the percentage of production units that pass quality inspection on the first attempt — no rework, no repair, no re-inspection. It is the truest measure of process quality because it reveals the full cost of getting things wrong.
A unit that is reworked and then passes is not counted as a first-pass good unit. This is the critical distinction between FPY and general yield.
The Formula
FPY = (Good Units ÷ Total Units Started) × 100%Where Good Units are those passing inspection on the first attempt only.
Benchmarks
| Level | FPY | Notes |
|---|---|---|
| Excellent | >95% | Best-in-class |
| Good | 90–95% | Solid quality performance |
| Acceptable | 85–90% | Room for improvement |
| Needs Improvement | <85% | Significant quality issues |
Typical Values by Industry
- Automotive: 95–99%
- Electronics: 90–95%
- Aerospace: 98–99%
- Consumer Goods: 85–95%
Data Requirements
| Source | Required | What You Need |
|---|---|---|
| Machine Data | Yes | Total units started, good count (first pass), rework count, reject count |
| QMS | Optional | Detailed defect data by type (for root cause analysis) |
First Pass Yield is a Phase 2 metric — it requires reliable quality inspection data, not just production counts.
Why It Matters
- True process capability measure — reveals how well your process performs inherently, without the crutch of rework
- Exposes the Hidden Factory — the rework and repair effort that consumes resources but produces no additional output
- Reduces cost of poor quality — every unit that passes first time avoids rework labour, materials, and delay
- Improves customer satisfaction — higher first-pass quality correlates with fewer field issues
- Feeds OEE Quality component — FPY is the input for the Quality factor in OEE
The Hidden Factory
When FPY is 90%, it looks acceptable. But it means 10% of your production is being reworked, repaired, or scrapped. That rework consumes labour, machine time, and materials — effectively running a “hidden factory” within your operation that produces no additional output. Improving FPY eliminates this hidden cost.
Common Pitfalls
- Including reworked parts as “good” — this is general yield, not FPY, and it hides the true cost of quality problems
- Not tracking units requiring minor touch-up — if it needed any intervention, it didn’t pass first time
- Inconsistent inspection criteria across shifts or inspectors — FPY is only meaningful if the standard is consistent
Best Practices
- Define clearly what constitutes “pass” versus “fail” before you start measuring
- Track FPY by product type for meaningful comparison
- Investigate sudden drops immediately — they usually indicate a process change
- Use Pareto analysis to identify the top defect types driving FPY down
- Correlate FPY with process parameters (temperature, pressure, speed) to find root causes
- Calculate cost impact: (1 − FPY%) × production value = cost of poor quality
Related Metrics
- OEE — FPY feeds into the Quality component
- Defect Rate — the inverse view (what percentage fails)
- Scrap Rate — units that cannot be reworked at all
- Rolled Throughput Yield — FPY across multiple process steps