Quality calculator
First Pass Yield Calculator
First pass yield (FPY) is the percentage of units that pass inspection cleanly the first time — no rework, no second pass, no touch-up. Lean and Six Sigma practitioners prize it over plain yield because it exposes the hidden factory: all the rework that final yield numbers quietly absorb. A line can ship 97% good and still have a mediocre FPY if a third of those units needed fixing. Tracking FPY tells you what your process does right the first time, which is the real driver of cost, capacity, and lead time.
What this calculator does
- Measure how many units pass the first time without rework.
- Use when rework hides process quality problems.
- It computes the share of units that passed inspection on the first attempt, plus the rework rate, fail rate, and the final pass rate after rework.
Formula used
- First pass yield = passed first time ÷ total units
- Rework rate = reworked units ÷ total units
Inputs explained
- Total units: undefined
- Passed first time: undefined
- Reworked units: undefined
- Failed / scrapped units: undefined
How to use the result
- Use it whenever you want to measure true process capability and quantify the cost of rework that final yield hides.
- FPY for one step does not capture compounding across a multi-step line; chain steps with rolled throughput yield for the end-to-end picture.
Current U.S. benchmarks
- U.S. manufacturing runs at 75.6% of capacity (Federal Reserve, May 2026). New factory orders are up 2.3% year over year (Census).
Common questions
- How do you calculate first pass yield? Divide units that passed the first time by total units, then multiply by 100. With 1,090 of 1,200 units passing first time, FPY is 1,090 / 1,200 = 90.83%.
- What is the difference between first pass yield and final yield? First pass yield (90.83% here) only credits units that passed without rework. Final pass rate (97.08%) credits everything that shipped after rework. The 6.25-point gap is your hidden rework factory.
- What is a good first pass yield? World-class assembly targets 95%+ FPY, and Six Sigma programs push toward 99%+. The example's 90.83% is acceptable but signals meaningful rework worth attacking, given the 6.25% rework rate.
- Why is first pass yield lower than overall yield? Because FPY refuses to count reworked units as wins. Here, the 75 reworked and a recovered share push final pass rate to 97.08%, but FPY stays at 90.83% — that difference is exactly the work you did twice.
- What does rework rate tell me? Rework rate is reworked units divided by total — 75 / 1,200 = 6.25% here. It quantifies how many units needed a second touch, which is direct hidden labor and a prime target for FPY improvement.
Last reviewed 2026-05-12.