First Pass Yield & RTY Calculator
Enter your process steps and defect counts to calculate First Pass Yield per step, Rolled Throughput Yield, DPMO, and sigma level. Find your hidden factory.
Process Steps
Enter the number of units inspected and defects found at each step. Defects include rework, scrap, and any unit requiring correction.
| # | Step Name | Units In | Defects | FPY |
|---|
Yield & Sigma Reference
| Sigma | Yield | DPMO | Class |
|---|---|---|---|
| 2σ | 69.15% | 308,538 | Non-competitive |
| 3σ | 93.32% | 66,807 | Average |
| 4σ | 99.379% | 6,210 | Competitive |
| 5σ | 99.977% | 233 | World-class |
| 6σ | 99.99966% | 3.4 | Best-in-class |
What Is First Pass Yield (FPY)?
First Pass Yield measures the percentage of units that pass through a process step correctly the first time — without rework, repair, or scrap. Unlike final yield, which counts reworked units as good, FPY reveals the true cost of quality by exposing every touch-up, reinspection, and sorting operation hidden inside your process. FPY = (Units In − Defects) / Units In.
FPY is a foundational metric in Six Sigma and lean manufacturing. It directly connects to process capability — a process with a Cpk of 1.33 (4σ) produces ~63 PPM defective and an FPY of ~99.99%. When FPY drops below 95% at any step, that step is a prime target for root cause analysis and improvement.
Rolled Throughput Yield and the Hidden Factory
Rolled Throughput Yield (RTY) is the probability that a unit passes through all process steps without any defect. It is calculated by multiplying the FPY of each step: RTY = FPY1 × FPY2 × … × FPYn. Because probabilities multiply, RTY drops faster than most engineers expect — a 5-step process with 97% FPY at each step has an RTY of only 85.9%.
The gap between final yield and RTY is the hidden factory — all the rework, reinspection, and correction that adds cost but not value. A process shipping 99% good product might have an RTY of 80% if rework loops exist at multiple steps. The hidden factory is invisible to traditional yield metrics but directly impacts cost of poor quality (COPQ), cycle time, and capacity. Use value stream mapping to visualize where yield loss occurs and quantify the waste.
How to Improve RTY
Start with the worst step — the one with the lowest FPY. Small improvements at the bottleneck have the largest RTY impact. Use these tools in sequence:
- Identify — use Pareto analysis to find the top defect types at the worst step
- Analyze — apply root cause analysis (5 Why, fishbone diagram) to find systematic causes
- Control — implement SPC control charts to detect process shifts before they produce defects
- Prevent — add mistake-proofing (poka-yoke), standard work, and design changes to eliminate the root cause
- Verify — re-measure FPY after each improvement cycle to confirm RTY gains
Yield Benchmarks by Industry
Target RTY varies by process complexity and industry requirements:
- RTY ≥ 99% — semiconductor fabrication, pharmaceutical manufacturing
- RTY ≥ 95% — world-class discrete manufacturing, automotive assembly
- RTY 85–95% — competitive general manufacturing, electronics assembly
- RTY < 85% — significant hidden factory waste; systematic improvement needed
Even a 2–3% RTY improvement often delivers significant cost savings by eliminating rework labor, reducing cycle time, and freeing capacity. Track yield trends over time with SPC dashboards to ensure gains are sustained.
Track yield across your value stream
Map your entire process with value stream mapping, SPC control charts, and root cause analysis. Find where yield drops and fix it with data.
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