Definition
The proportion of products that pass through the process without defects at one time; the caliber is the ratio of good practices per process, not the rate of the lowest process (the error of the pedagogic naming).
In detail
First Pass Yield (FPY) is a key metric for measuring process quality, defined as the proportion of products that pass through the entire process without defects on the first attempt. It is calculated by multiplying the yields of each process, not by taking the lowest value. It reveals the waste of the hidden factory and helps identify improvement opportunities. In the Danaher Six Sigma curriculum, FPY for an entire process is the product of each step's first-pass yield — the same calculation as RTY (Rolled Throughput Yield); a unit that only passes after rework does not count as first-pass. Typical outputs include FPY data, trend charts, and improvement projects.
Example in practice
A factory found that final inspection pass rate was high, but FPY was low. By calculating the product of yields at each process, they discovered significant rework in intermediate processes. The team improved the bottleneck process, FPY increased, rework costs decreased, and delivery efficiency improved.