Yield in Six Sigma: FPY, RTY, and Final Yield Explained

In Six Sigma, yield measures the percentage of units that meet requirements out of the total units produced. It is not a financial or investment term. Three types of yield matter most. Final yield counts every good unit at the end, including units fixed through rework.

First pass yield (FPY) counts only units that passed correctly the first time, with no rework at all. Rolled throughput yield (RTY) multiplies the first pass yield of every step in a multi-step process together, which reveals a hidden problem most teams miss. A process can show a high final yield while its true first pass yield hides significant rework costs, a pattern often called the hidden factory.

Quick-Reference Table: Types of Yield Compared

Yield Type	What It Counts	Includes Rework?
Final yield	Good units at the very end of the process	Yes
First pass yield (FPY)	Units correct the first time, at one step	No
Rolled throughput yield (RTY)	Combined first pass yield across every step in a process	No

Key Takeaways

• Yield in Six Sigma measures output quality, not financial return. It has no connection to investment or dividend yield.
• Final yield can hide real problems. A process can show 98 percent final yield while quietly reworking a large share of its units to get there.
• First pass yield is the honest number. It only counts units that succeeded without any correction.
• Rolled throughput yield multiplies FPY across steps. A multi-step process with several 95 percent steps often produces a much lower combined RTY than any single step suggests.
• The gap between final yield and RTY reveals the hidden factory. This is the rework, scrap, and correction effort a company pays for but never counts as waste.
• Yield connects directly to sigma level. A higher RTY corresponds to a higher sigma level and a lower predicted defect rate.

What Is Yield in Six Sigma?

Yield measures the percentage of output that meets requirements, out of everything a process produces. A process that starts with 1,000 units and ends with 950 acceptable units has a yield of 95 percent.

This sounds simple, but the word “yield” hides an important question: acceptable how? Did those 950 units pass correctly the first time, or did some of them need rework, repair, or a second attempt before they counted as acceptable? This question is exactly what separates the three types of yield covered below.

Final Yield: The Number Most People See First

The Final yield counts every unit that eventually meets specification, whether it passed the first time or needed correction along the way.

Final Yield = (Good units at the end) divided by (Total units started)

This number looks good on a report. It also hides the cost of getting there. A batch of 100 units where 90 pass immediately and 10 require rework before passing still shows a 100 percent final yield, even though 10 percent of the batch consumed extra time, labor, and material to fix.

First Pass Yield: The Honest Number

The First pass yield (FPY) counts only the units that met requirements on the very first attempt, with zero rework, repair, or correction.

First Pass Yield = (Units that passed correctly the first time) divided by (Total units started)

Using the same example, if 90 out of 100 units passed without any correction, the first pass yield is 90 percent, not 100 percent. This is the number that actually reflects how well the process performs on its own, without the hidden cost of fixing mistakes afterward.

Rolled Throughput Yield: Seeing the Whole Process

Most real processes involve multiple steps, not just one. Rolled throughput yield (RTY) multiplies the first pass yield of each step together, revealing how the process performs as a whole.

RTY = (FPY of Step 1) times (FPY of Step 2) times (FPY of Step 3), and so on for every step

This calculation often produces a surprising, much lower number than any single step suggests. A four-step process where each step individually runs at 95 percent first pass yield does not produce a 95 percent overall result.

A Worked Example: Why RTY Reveals the Hidden Factory

Consider an order fulfillment process with four steps: order entry, inventory pick, packing, and shipping label creation. Each step individually looks strong.

Step	First Pass Yield
Order entry	95%
Inventory pick	95%
Packing	95%
Shipping label creation	95%

Calculating RTY:

RTY = 0.95 times 0.95 times 0.95 times 0.95 = approximately 81.5%

A process where every individual step looks like it is running at 95 percent actually only delivers a true first-time-right result of about 81.5 percent overall. The remaining 18.5 percent of orders required some form of correction somewhere along the four steps, even though no single step looked alarming on its own.

This gap, between what each step appears to show and what the whole process actually delivers, is the hidden factory. It represents rework capacity a company is paying for without tracking it as a defined cost or defect.

Why the Hidden Factory Matters for Cost and Capacity?

The hidden factory consumes real resources that never appear as a formal line item. Extra labor hours spent correcting mistakes, extra material used in rework, and extra time spent recreating a shipping label all cost money, even though a final yield report might show the process running smoothly.

A team relying only on final yield to judge process health can completely miss this cost. A team that calculates RTY instead sees the true picture immediately, which is exactly why RTY is considered the more rigorous and informative metric.

How to Calculate Yield: Step-by-Step

1. Map every step in the process. Identify each distinct stage where a unit could pass or fail.
2. Measure the first pass yield at each individual step. Track units that succeeded without any rework, separately from units that eventually passed only after correction.
3. Multiply every step’s first pass yield together. This produces the rolled throughput yield for the entire process.
4. Compare RTY against final yield. The size of the gap between these two numbers shows how much hidden rework the process currently absorbs.
5. Target the step with the lowest first pass yield first. Improving the weakest step in the chain often produces the biggest overall RTY improvement.

Also See: Cutter Yield Stabilization Case Study

Yield’s Connection to Sigma Level and DPMO

Yield and sigma level describe the same underlying process performance, from two different angles. A higher rolled throughput yield corresponds to a higher sigma level, and a lower predicted defect rate, expressed as defects per million opportunities (DPMO).

Approximate RTY	Approximate Sigma Level
30.9%	1 sigma
69.2%	2 sigma
93.3%	3 sigma
99.4%	4 sigma
99.98%	5 sigma
99.9997%	6 sigma

This table shows why the four-step example above, with an 81.5 percent RTY, sits below even a full 3 sigma level. Converting yield into a sigma level allows a team to benchmark their process against a widely recognized performance scale.

Common Mistakes When Measuring Yield

Reporting final yield as if it were first pass yield. This is the single most common and most misleading mistake. It makes a process look far healthier than it actually performs.

Skipping RTY on multi-step processes. Measuring yield only at the very last step misses exactly where rework accumulates along the way.

Not tracking which step causes the most rework. Without step-by-step FPY data, a team cannot target the actual bottleneck driving the overall RTY down.

Confusing “yield” with the unrelated financial term. In a business or process improvement context, yield refers to output quality, not investment return, dividends, or bond performance, a completely separate concept from a different field.

Also Read: Six Sigma in Food and Beverage Manufacturing: Control Yield & Quality

Frequently Asked Questions (FAQs) on Yield in Six Sigma

What does yield mean in Six Sigma?
Yield measures the percentage of units that meet requirements out of the total units a process produces. It is a quality and output metric, unrelated to financial or investment yield.

What is the difference between final yield and first pass yield?
Final yield counts every good unit at the end of a process, including units that needed rework to pass. First pass yield counts only units that passed correctly on the first attempt, with no correction at all.

What is rolled throughput yield?
Rolled throughput yield (RTY) multiplies the first pass yield of every step in a multi-step process together. It reveals the true combined performance of the whole process, which is often much lower than any single step suggests on its own.

Why is rolled throughput yield usually lower than each step’s individual yield?
Because RTY multiplies probabilities together across every step, small losses at each stage compound. A process with several strong-looking 95 percent steps can still produce an overall RTY well below 90 percent once every step is combined.

What is the hidden factory in Six Sigma?
The hidden factory refers to the rework, correction, and scrap effort a process absorbs that never shows up in a final yield report. It represents real cost and lost capacity that only becomes visible when a team calculates first pass yield and RTY instead of relying on final yield alone.

How does yield relate to sigma level?
A higher rolled throughput yield corresponds to a higher sigma level and a lower predicted defect rate, measured in defects per million opportunities. This connection allows a team to benchmark their process yield against a standardized performance scale.

How do I improve my process’s rolled throughput yield?
Measure first pass yield at each individual step first, then focus improvement efforts on the step with the lowest yield. Since RTY multiplies every step together, improving the weakest link typically produces the largest gain in overall process performance.

Final Words

Yield in Six Sigma answers a specific question: how much of what a process produces actually meets requirements, and does that number include hidden rework or not? Final yield, first pass yield, and rolled throughput yield each answer that question at a different level of honesty.

The gap between a comfortable final yield number and a much lower RTY reveals the hidden factory, the rework and correction cost a process pays for without ever recording it as a formal defect. Calculating RTY, not just final yield, is what turns a vague sense that “quality is fine” into a precise, defensible measurement of how a process truly performs.

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Related Articles

• Rolled Throughput Yield (RTY)
• First Pass Yield (FPY)
• First Time Yield (FTY) in Manufacturing
• Hidden Factory
• DPMO (Defects Per Million Opportunities): Formula, Sigma Level Table