Rolled Throughput Yield (RTY)

Introduction: RTY

Rolled Throughput Yield (RTY) is a key metric in quality management and Lean Six Sigma that measures the probability of a product or service passing through all process steps without defects or rework. Unlike single-step measures, RTY captures the cumulative quality performance of an entire process. It reflects how each stage contributes to overall success and helps identify hidden inefficiencies that may not appear when analysing steps individually.

Background

While individual process steps often show high yields, the combined effect of even small defect rates across multiple steps can significantly reduce the total output quality. RTY was introduced to make this cumulative effect visible. By providing a more accurate picture of process performance, it enables teams to focus improvement efforts where they have the greatest impact. In Lean Six Sigma, RTY is commonly used alongside metrics such as Defects per Million Opportunities (DPMO) and First Pass Yield (FPY) to evaluate and optimise end-to-end capability.

Key Elements / Features

RTY is calculated by multiplying the First Pass Yield (FPY) of each process step: RTY=FPY1 ×FPY2 ×…×FPYn

Each FPY represents the fraction of units that pass through a step without rework or rejection.

For example, if:

• Step 1 FPY = 0.90 (90%)
• Step 2 FPY = 0.80 (80%)
• Step 3 FPY = 0.95 (95%)

then:

RTY = 0.90 × 0.80 × 0.95 = 0.684 (68.4%)

This means only 68.4% of units complete the full process without requiring any rework. The result highlights how small inefficiencies in each step compound across the process.

Applications / Examples

• Manufacturing: Measuring the true defect-free yield across multiple assembly stages.
• Healthcare: Evaluating error-free completion of multi-step treatment or lab procedures.
• Service Processes: Tracking how many customer requests are completed correctly the first time.
  Example: A production line with high step-level yields (above 90%) still finds that less than 70% of units pass through the full process without rework, prompting targeted improvements.

Relevance / Impact

RTY provides a realistic measure of overall process capability, revealing weaknesses that single metrics can hide. By improving low-yield steps, organisations can significantly raise total process efficiency, reduce rework and waste, and improve customer satisfaction. RTY thus plays a vital role in guiding continuous improvement and sustaining high-quality performance.

See also

• First Pass Yield (FPY)
• Yield
• Defects per Million Opportunities (DPMO)
• Process Capability