Formula & Calculator
First Pass Yield
Measures the percentage of units that pass through a process correctly the first time, without any rework or scrap.
Interpretation
FPY (%) = (Units Passing Without Rework / Total Units Started) × 100. Percentage of units that pass inspection on the first attempt without rework. Measures process quality and efficiency. Used in lean and Six Sigma.
Variables
| Symbol | Quantity | Unit |
|---|---|---|
| FPY | First pass yield | % |
| Units Passing Without Rework | Units completed correctly with no rework | units |
| Total Units Started | Total units that entered the process | units |
What it means
First Pass Yield (FPY) is a quality metric that measures the proportion of units that are produced correctly the first time, without requiring any rework or repair. It is calculated by dividing the number of units that pass final inspection without rework by the total number of units that entered the process, multiplied by 100. A high FPY indicates a process that produces quality output consistently, reducing waste, cost, and lead time. Low FPY suggests process problems, training needs, or equipment issues. In lean manufacturing and Six Sigma, FPY is a key indicator of process performance and a driver of continuous improvement. It is often used together with other metrics like rolled throughput yield and defect rate. Managers use FPY to set quality goals, identify areas for improvement, and reduce the cost of poor quality. Understanding FPY is essential for quality managers, process engineers, and production supervisors to monitor and improve process effectiveness.
Worked example
First Pass Yield – Two Examples
Real‑World| Parameter | Value |
|---|---|
| Units started | 1,000 |
| Passing first time | 920 |
| Parameter | Value |
|---|---|
| Units started | 500 |
| Passing first time | 470 |
Common mistakes
- Units passing without rework: Units that meet quality standards on the first pass – no rework or repairs.
- Total units started: The total number of units that entered the process.
- Percentage: Multiply by 100 – result is a percentage.
- Interpretation: FPY measures the effectiveness of the process in producing good parts the first time.
- Hidden factory: Low FPY indicates significant rework (non‑value‑added work).
Applications
First Pass Yield (FPY) is the percentage of units that pass through a manufacturing process without requiring rework or repair, calculated as (units passing without rework / total units started) × 100%. This metric reflects the quality of the process and the efficiency of production. High FPY indicates a stable process with minimal defects, reducing rework costs and lead times. Operations managers use FPY to monitor process health, to evaluate the effectiveness of improvement initiatives, and to identify areas where additional quality controls are needed. FPY is a key performance indicator (KPI) in many industries, including electronics, automotive, and consumer goods. By tracking FPY, organisations can drive continuous improvement and reduce the cost of poor quality.
- Quality monitoring in manufacturing and assembly processes
- Continuous improvement and defect reduction programmes
- Process validation and product launch assessment
- Cost of quality analysis and reduction of rework
- Supplier performance and manufacturing efficiency measurement
Frequently Asked Questions
First Pass Yield is the percentage of units that pass through a process without any rework or scrap on the first attempt. It is calculated as FPY (%) = (Units Passing Without Rework / Total Units Started) × 100.
Confusing first pass yield (units correct with no rework at all) with final yield (units eventually passing after rework). Final yield is higher because it includes units that were reworked. FPY is a more stringent measure of process quality and reveals the hidden cost of rework.
FPY is a key metric of process efficiency. A low FPY indicates that a significant portion of production is reworked, wasting time, materials, and capacity. Improving FPY reduces cost and lead time.
For a process with multiple steps, FPY is the product of the yields at each step, assuming rework is not allowed. That is, FPY = Yield_step1 × Yield_step2 × … × Yield_stepn.
FPY is typically the yield at a single step or the product of step yields without rework. RTY is specifically the product of step yields, often used to estimate the overall probability of a defect‑free unit through the entire process. They are similar but RTY is a standard term.
It means that 95 out of every 100 units produced are made correctly the first time, without any rework. The remaining 5% require some form of correction.
- Identify root causes of defects and eliminate them.
- Improve process control (reduce variation).
- Implement mistake‑proofing (poka‑yoke).
- Train operators.
- Standardise work.
FPY is a component of OEE (the Quality factor). OEE = Availability × Performance × Quality, where Quality is essentially FPY (good units / total units). So improving FPY directly improves OEE.
- Does not account for the cost or severity of rework.
- May not capture the impact of scrap.
- If rework is allowed and counts as passing, FPY may be understated.
- Does not reflect customer satisfaction with quality.
If you know the number of units that required rework, FPY = (Units – Reworked Units) / Units × 100. For example, if 1000 units started and 50 had to be reworked, FPY = (1000‑50)/1000 = 95%.