What is First Pass Yield (FPY)?
First Pass Yield (FPY) is the percentage of units that pass through a process correctly the first time, with no rework, repair, or scrap. It divides the good units produced on the first attempt by the total units started, then multiplies by 100. An FPY of 100% means every unit was made right the first time.
How First Pass Yield is calculated
The formula is straightforward:
FPY = (Good Units Produced Without Rework ÷ Total Units Entering the Process) × 100
The critical detail is the numerator. Only units that pass on the first attempt count. If 1,000 units enter a process, 950 pass immediately, and another 30 are reworked until they pass, the final good count is 980 — but the First Pass Yield is 950 ÷ 1,000 = 95%, not 98%. FPY deliberately ignores rework, because rework is hidden waste: it costs labor, time, and material even when the unit is eventually shipped.
First Pass Yield vs. Rolled Throughput Yield
A single FPY number describes one process step. Real production lines have many steps in sequence, and each has its own yield loss. Rolled Throughput Yield (RTY) captures the whole chain by multiplying the FPY of every step:
RTY = FPY₁ × FPY₂ × FPY₃ × … × FPYₙ
Because the values are multiplied, RTY is always lower than the weakest single step. Five steps each at 95% FPY yield an RTY of about 77% — meaning fewer than four in five units clear the entire line untouched. This exposes the “hidden factory” of rework that end-of-line inspection alone conceals.
Why First Pass Yield matters
- It surfaces hidden cost. A high final-yield number can mask a mountain of rework. FPY makes that rework visible.
- It drives quality upstream. Improving FPY means fixing the root cause of first-time failures rather than inspecting and repairing after the fact.
- It supports lean and Six Sigma. FPY and RTY are standard metrics in DMAIC projects and lean initiatives, quantifying process capability and the cost of poor quality.
- It protects throughput. Units that pass the first time do not clog rework loops, so capacity and lead time improve.
Common pitfalls
- Counting reworked units as first-pass. The most frequent error; it inflates FPY and hides the problem the metric exists to reveal.
- Measuring only at the end of the line. Step-level FPY pinpoints where defects originate; a single line-end number does not.
- Tracking without acting. FPY is a diagnostic. Without root-cause analysis and corrective action, the number does not move.
How VSight helps
Most first-time failures trace back to a step done incorrectly, skipped, or performed inconsistently — the same causes lean and Six Sigma teams target when they work on FPY. With VSight Workflow, teams turn SOPs into digital work instructions and checklists that standardize every step, enforce sequence, and capture each result, reducing the operator errors that create defects and rework. As a connected worker platform, VSight also provides AR remote assistance — a live expert viewing a technician’s camera feed with augmented-reality annotation — so difficult steps and unexpected problems get resolved correctly the first time instead of triggering a rework loop. VSight is GDPR, HIPAA, and ISO 27001 certified, which matters for regulated operations that must document controlled, repeatable processes.
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Related terms: OEE, Six Sigma, poka-yoke
Frequently asked questions
What is First Pass Yield (FPY)? First Pass Yield is the percentage of units that pass through a process correctly the first time, without any rework, repair, or scrap. It is calculated by dividing the number of good units produced on the first attempt by the total number of units started, then multiplying by 100.
How is First Pass Yield calculated? FPY equals good units produced without rework divided by total units entering the process, times 100. Only units that pass the first time count in the numerator, so any unit that was reworked and later passed is still excluded, which is what separates FPY from a simple end-of-line yield.
What is the difference between First Pass Yield and Rolled Throughput Yield? First Pass Yield measures the first-time success of a single process step. Rolled Throughput Yield (RTY) multiplies the FPY of every step in a multi-stage process to reveal the true probability that a unit passes the entire line with no rework, which is almost always lower than any single step’s FPY.
How does VSight help improve First Pass Yield? VSight Workflow delivers digital work instructions and checklists that standardize each step and reduce the operator errors that create defects. VSight AR remote assistance puts a live expert on a technician’s camera view with AR annotation, so problems get resolved correctly the first time instead of causing rework.