Key takeaways
Short answer: First pass yield looks at one operation: of the units that entered, how many passed without rework or scrap? Rolled throughput yield looks at the whole chain: multiply every step's FPY together and you get the odds a unit makes it through the entire process clean. The two diverge fast — five steps at 95% each is not 95% overall, it is about 77% — and that gap is the rework most metrics never show. For how this feeds production, see OEE for manufacturing.
First pass yield is a single-step quality metric: of the units that entered an operation, what fraction came out good the first time, with no rework, no touch-up, no second attempt? The phrase first pass is the important part. A step can ship 100% good units to the next operation and still have a poor FPY if half of them were reworked to get there. FPY counts only what passed cleanly on the first attempt, which is why it exposes effort that final yield hides. It is the honest measure of how capable one operation really is.
Rolled throughput yield asks a harder question: what is the probability that a single unit passes every step of the process without a defect at any of them? You calculate it by multiplying the FPY of each step together. Because you are multiplying fractions, RTY is always lower than your worst individual step — and it falls quickly as steps accumulate. RTY is the metric that reflects what a customer actually experiences: not whether any one station is good, but whether the whole process can deliver a clean unit end to end.
The gap between high single-step yields and a lower RTY has a name: the hidden factory. It is all the rework, retest, and touch-up that keeps final yield looking acceptable while quietly consuming capacity, labour, and time. Each rework loop is real work that produced nothing new — a unit you already made, made again. Because that effort is buried inside steps that still pass, it rarely shows up on a yield report. RTY drags it into the light by refusing to count anything that needed a second attempt. Recovering RTY losses is often the cheapest capacity you can find.
Picture a five-step process, each step running a respectable 95% first pass yield. Intuition says the line is 95% good. The math says otherwise: 0.95 × 0.95 × 0.95 × 0.95 × 0.95 ≈ 0.774, so only about 77% of units pass all five steps clean. Nearly a quarter needed rework somewhere. Now improve one weak step from 95% to 99% and RTY climbs to about 81% — a four-point gain in throughput from fixing a single station. That leverage is the whole point: RTY tells you not just that there is hidden loss, but which step is leaking the most.
Use first pass yield to manage and improve an individual operation — it is the right granularity for a process owner tuning one station. Use rolled throughput yield to understand the process as a whole, set realistic delivery expectations, and prioritise which step to fix first. FPY answers is this station capable; RTY answers can this line deliver a clean unit, and where is it losing them. Reporting only final yield gives you neither — it hides both the rework inside each step and the compounding loss across them.
The quality factor in OEE counts only good units produced right the first time — which makes it conceptually close to first pass yield at the line level. Rework that RTY exposes hits OEE twice: it lowers the quality factor directly, and the time spent reprocessing eats into availability and performance too. So a process with a weak RTY rarely has just a quality problem; it has an OEE problem spread across all three factors. Tracking yield the first-pass way keeps OEE honest and connects it to the six big losses.
Fabrico captures good-versus-reject counts at the point of production and feeds them into the quality factor of live OEE, so the rework that hides in final yield shows up where it belongs. Seeing first-time-good quality next to availability and performance is what lets a team find the hidden factory and target the step that is leaking the most. Book a demo to see first-pass quality on your lines.
First pass yield is the share of units that pass one step right the first time. Rolled throughput yield multiplies the first pass yields of every step to give the probability a unit passes the entire process without rework. RTY is always lower than any single FPY.
Multiply the first pass yield of each process step together. For example, five steps at 95% each give an RTY of 0.95 to the fifth power, about 77%, not 95%.
Because RTY is the product of several fractions less than one. Each additional step multiplies the running total down, so the whole-process yield is always below your worst single step.
The hidden factory is the rework, retest, and touch-up that keeps final yield looking acceptable while consuming capacity and labour. RTY exposes it by counting only units that pass each step on the first attempt.
The quality factor in OEE counts only units made right the first time, much like first pass yield at the line level. Rework lowers the quality factor and also eats availability and performance, so weak yield drags OEE down across all three factors.
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