First Pass Yield vs Rolled Throughput Yield vs Final Yield — here’s a question that trips up a lot of quality engineers: if your line finishes the week at 97% yield, does that mean 97% of units sailed through without a hitch? Not necessarily. It might mean 97% of units eventually passed — after some of them went through rework three or four times. That’s the gap between First Pass Yield, Rolled Throughput Yield, and Final Yield, and it matters more than most teams realize.
FPY measures what percentage of units pass a single step on the very first attempt — no rework, no touch-ups. RTY multiplies that across every step in your process, giving you the probability that a unit travels the whole line defect-free from the start. Final Yield counts good units at the end, including ones that were fixed along the way. Each metric is telling you something real — but they’re answering different questions. This guide walks through all three with formulas, a worked example, and a plain-English decision framework for when to use each.
Yield metrics tell you how much of your production process is working correctly on the first try — and how much is being quietly consumed by rework, inspection loops, and scrap. In lean and Six Sigma manufacturing, yield is more than a number on a daily report; it is a direct indicator of process health, resource waste, and hidden cost.
The three most commonly tracked yield metrics are First Pass Yield, Rolled Throughput Yield, and Final Yield. Each one measures something subtly different, and using the wrong one for the wrong purpose can give you a falsely optimistic picture of your production line. According to ASQ, hidden rework — also called the “hidden factory” — is one of the leading causes of untracked waste in manufacturing operations.
First Pass Yield (FPY) measures the percentage of units that successfully pass through a single process step without requiring any rework, repair, or scrapping on the first attempt. It is a step-level metric: it tells you how well one specific operation in your process is performing.
FPY = (Units passing without rework or scrap) ÷ (Total units entering the step) × 100
Take a 3-step assembly process as an example:
Step 1 is where the real problem lives at 94%. Without per-step FPY, that distinction disappears into a blended average.
RTY asks: what’s the probability that a unit makes it through your entire process without being touched for rework even once? You multiply the FPY of every step together.
RTY = FPY₁ × FPY₂ × … × FPYₙ
Using the same 3-step process: RTY = 0.940 × 0.965 × 0.978 = 88.7%
Every individual step had FPY above 94% — but the RTY is only 88.7%. That 11.3% gap represents units reworked at least once somewhere on the line. According to iSixSigma, hidden factory costs can represent 15–40% of total operating costs in some manufacturing environments.
Final Yield counts all good units at the end of the process — including reworked ones. A unit reworked four times counts the same as one that sailed through clean.
Final Yield = (Total good units out, including reworked) ÷ (Total units entering Step 1) × 100
Using the same process: 978 units passed out of 1,000 entered. Final Yield = 97.8% — versus RTY of 88.7%. The 9.1% gap is your hidden factory.
Here is how all three metrics compare across the attributes that matter most:
| Attribute | First Pass Yield (FPY) | Rolled Throughput Yield (RTY) | Final Yield |
|---|---|---|---|
| What it measures | Quality at one process step | Cumulative quality across all steps | Output quality including reworked units |
| Formula | Good units ÷ Total in (per step) | FPY₁ × FPY₂ × … × FPYₙ | Total good out ÷ Total in |
| Counts rework? | Yes — reduces FPY | Yes — compounds across steps | No — reworked = good |
| Reveals hidden factory? | Partially (per step only) | Yes — fully | No |
| Best use | Step-level troubleshooting | End-to-end process audit | Customer-facing reporting |
| Optimism level | Moderate | Most realistic | Most optimistic |
FTY counts reworked units as good if they ultimately pass — closer to Final Yield at the step level. FPY only counts units that passed on the very first attempt. For RTY calculations in Six Sigma DMAIC projects, always use the strict FPY definition. According to the iSixSigma dictionary, FPY is the preferred term in DMAIC Measure phase work.
Use FPY when you need to diagnose which specific step is generating the most defects and rework:
Use RTY when you need the true cost of your entire process:
Use Final Yield for customer-facing quality reporting:
FPY measures quality at one process step. RTY multiplies FPY across every step to give you the probability of a unit passing the entire process defect-free. RTY is always lower than any individual step FPY.
FPY excludes reworked units. Final Yield includes them. Final Yield will always be higher than RTY on the same process — the gap between the two is your hidden factory.
It depends on industry. Pharma targets 99%+, automotive 95–99%, electronics 92–97%. Any step below 90% warrants immediate investigation.
A CMMS like Cryotos addresses the leading root cause of FPY losses — equipment degradation. It schedules preventive maintenance before machines generate defects, triggers corrective work orders when parameters deviate, and logs all rework so teams can calculate accurate FPY and RTY from real operational data.
Tracking FPY, RTY, and Final Yield gives your team the full picture. Cryotos CMMS connects maintenance operations directly to quality metrics — every work order, PM schedule, and downtime event feeds into the data your team needs. Explore what Cryotos can do for your production quality.
Cryotos AI predicts failures, automates work orders, and simplifies maintenance—before problems slow you down.
