First Pass Yield (FPY

Lean Six Sigma: First Pass Yield (FPY) vs. Final Process Yield

In manufacturing quality control, relying solely on Final Yield (the percentage of finished parts leaving the facility) masks enormous operational waste:

• The Fallacy of Final Yield: A plant with a 99% Final Yield may actually be reworking 30% of parts behind the scenes before re-inspecting them, incurring massive overtime labor, component damage, and delayed delivery.

• The Hidden Factory Concept: First coined by Armand Feigenbaum, the "Hidden Factory" refers to the unbudgeted capacity, floor space, and labor consumed exclusively by fixing, re-testing, and tweaking defective units.

• Rolled Throughput Yield (RTY): RTY multiplies the true first-pass yields across every discrete sequential workstation), revealing the true probability that a unit will pass from raw material to finished goods with zero defects and zero rework.

How to Use This Calculator

Enter your Initial Starting Batch Size (Units Entering Step 1) (e.g. 1,000), Step 1 First Pass Yield (%) [e.g. SMT / Machining] (e.g. 96.5), Step 2 First Pass Yield (%) [e.g. Sub-Assembly] (e.g. 98.0), Step 3 First Pass Yield (%) [e.g. Soldering / Bonding] (e.g. 95.0), Step 4 First Pass Yield (%) [e.g. Final Assembly & Testing] (e.g. 99.2), and Average Rework / Touch-Up Cost per Defect (/unit) (e.g. 35.00 (Hidden factory labor and diagnostic cost)). Results update instantly as you type — adjust any value to compare scenarios.

The Formula

First Pass Yield (FPY) \& Rolled Throughput Yield (RTY) equations:

Single-Step First Pass Yield (FPY_i) = (Units In_i - Scrapped_i - Reworked_i) / (Units In_i)

Rolled Throughput Yield (RTY) = Π_i=1^k FPY_i = FPY_1 × FPY_2 × × FPY_k

Zero-Rework Units Completed = Starting Units × RTY

Defect Fallout Requiring Rework = Starting Units × (1 - RTY)

Hidden Factory Rework Cost = Defect Units × Unit Rework Cost

Cumulative Defects Per Unit (DPU) = -(RTY)

Worked Example

For example, evaluating a 4-step manufacturing process starting with 1,000 units, where Step 1 yield is 96.5\%, Step 2 is 98.0\%, Step 3 is 95.0\%, and Step 4 is 99.2\% with \35.00 average rework cost per defect: Rolled Throughput Yield is . Only 891 units make it through cleanly without any rework, while 109 units require rework loops, costing \3,815.00 in hidden factory rework expenses).

Understanding Your Result

For financial decisions, validate your result against your specific tax situation, current interest rate environment, and applicable regulations — these change frequently and vary by jurisdiction. A calculated estimate is a useful starting point; for decisions involving significant capital (more than one month's income), consult a certified financial planner (CFP) or CPA. Financial projections beyond 3–5 years carry increasing uncertainty — model a conservative, base, and optimistic scenario to understand the range of outcomes.