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First Pass Yield Calculator

Enter your production counts to find your first pass yield.

Result

90.50%
114 units
1,200 units

How it is calculated

Enter the number of units that entered the process step and the number that passed inspection the first time, with no rework and no scrap. The tool computes FPY = passed ÷ started × 100, shown as a percentage with two decimals, and the leftover started − passed, which it labels as units reworked or scrapped (it cannot tell the two apart). Started must be above zero, passed cannot be negative, and passed cannot exceed started, otherwise no result appears. The calculation is for a single step; for several steps in sequence, multiply their separate FPY values together.

Worked example

A line starts 1,200 units and 1,086 pass at the first inspection. FPY = 1086 ÷ 1200 = 0.905, and × 100 gives 90.50%. The units that did not pass first time are 1200 − 1086 = 114, which is the count of reworked or scrapped units. If those 114 units were later repaired and shipped, the final yield would look much better, but FPY stays at 90.50% because it only counts units that were right first time.

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Common mistakes

  • Counting reworked units that eventually passed as "passed". FPY counts only units that passed the first time without any rework, so entering all shipped units overstates the yield.
  • Entering the number of defects instead of the number of good units. The second box is the units that passed, so 114 defects out of 1,200 means entering 1,086, not 114.
  • Leaving scrapped units out of "started". Every unit that entered the step belongs in the starting count, including ones thrown away.
  • Multiplying defect counts rather than yields when combining several steps. Combine the percentages as fractions (0.905 × 0.95 and so on) to get the rolled yield.
  • Mixing time periods, for example this week's starts with last week's passes, which can push passed above started and produces no result.

Sources

About this calculator

First pass yield (FPY) is a manufacturing quality metric that measures the percentage of units completing a process step correctly on the first attempt, with no rework, repair or scrap required: FPY = (units started − units needing rework or scrapped) ÷ units started, expressed as a percentage. Unlike a final yield figure that only counts units that eventually shipped, FPY exposes hidden cost by counting a reworked-then-passed unit as a failure of the first pass, since rework consumes extra time, labor and material even if the unit is ultimately saved.

FPY is a core metric in lean manufacturing and Six Sigma quality programs, used by production managers and quality engineers to spot which process step is generating the most defects and to track whether process improvements are actually reducing rework rather than just catching more defects downstream. When a process has multiple sequential steps, multiplying each step's FPY together gives the rolled throughput yield, a stricter measure of true end-to-end process quality.

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Comments (1)

  • Editorial team

    A line can look healthy step by step and still be weak end to end. Five steps that each run at 95% sound fine, yet multiplying them gives 0.95 to the fifth power, about 77.4% of units right first time all the way through. Run this tool once per step, using each step's own started and passed counts, then multiply the percentages as fractions. How many steps does your process have, and which one drags the total down?

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