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First pass yield (FPY) calculator
First pass yield (FPY) is the share of units that get through a process step right the first time, with no rework, repair or scrap. Rolled throughput yield (RTY) multiplies the FPY of every step together: the chance that a unit gets through the whole process without a single fix.
FPY (each step)equalsUnits passed first time divided by Units in × 100
RTYequalsFPY step 1 × FPY step 2 × … × FPY step n
Pre-filled with the worked example. Passed first time means no rework, repair or scrap at that step; a reworked unit that later passes does not count.
Rolled throughput yield
81.3%
Of every 100 units started, about 81.3 get through all 4 steps with no rework or scrap.
Lowest step
Step 2
90.0% first pass yield
Reworked or scrapped
200 units
Across all steps
First pass yield by step
Next step
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How to calculate it
Count what went right the first time
For each step, count the units in, every unit that entered the step in the period, and the units passed first time, the ones that needed no rework, repair or scrap there. Their ratio is that step's first pass yield.
Multiply the step yields together for the rolled throughput yield. Steps that each look fine on their own can still leave a low RTY, because the losses compound: a unit has to survive every step.
The step with the lowest FPY is usually the place to start, and a root cause analysis there pays off fastest. To put a money value on the rework and scrap, use the cost of poor quality calculator.
Worked example
Illustrative numbers, not a benchmarkA four-step process handles 1,000 units at each step. First time through, 950 pass step 1, 900 pass step 2, 980 pass step 3 and 970 pass step 4.
- 1FPY step 1 = 950 ÷ 1,000 = 95%. Step 2 = 900 ÷ 1,000 = 90%.
- 2FPY step 3 = 980 ÷ 1,000 = 98%. Step 4 = 970 ÷ 1,000 = 97%.
- 3RTY = 0.95 × 0.90 × 0.98 × 0.97 = 0.8128 = 81.3%.
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<p style="font:13px/1.4 sans-serif"><a href="https://www.theleansuite.com/tools/first-pass-yield-calculator">First pass yield (FPY) calculator</a> by LeanSuite</p>How LeanSuite helps
LeanSuite lets you log quality issues from the floor, trace each one to its root cause and follow the corrective action through to closure.
See Quality ImprovementRead more
- Free template: Defect catalogue template with boundary samples
- First pass yield (FPY) in the lean glossary
- First Pass Yield: Definition, Calculation, and Improvement
- How to reduce scrap and rework: a worked month
- First Pass Yield: Definition, Calculation, and Improvement
- Cost of poor quality (COPQ) in the lean glossary
- Poka-yoke in the lean glossary
FAQ
First pass yield (FPY) calculator: common questions
Divide the units that passed a step the first time, with no rework, repair or scrap, by the units that entered the step, and multiply by 100. For example, 900 units passing first time out of 1,000 entering is an FPY of 90%.
Rolled throughput yield is the chance that a unit gets through every step of a process without any rework or scrap. It is the first pass yields of all the steps multiplied together, so four steps at 95%, 90%, 98% and 97% give an RTY of about 81.3%.
Final yield counts every unit that eventually ships, including units that were reworked along the way. First pass yield counts only units that were right the first time. The gap between the two is the rework a plant does to fix its own defects, often called the hidden factory.
Because a unit has to get through every step. If step 1 passes 95% first time and step 2 passes 90% of what reaches it, only 95% × 90% = 85.5% get through both untouched. An average of 92.5% would hide the losses compounding from step to step.
Yes. Units that were scrapped and units that were reworked or repaired both failed the first pass. Count them in the units that entered the step, and leave them out of the units that passed first time.
Every unit that misses the first pass costs something to rework or scrap, and those costs are internal failure costs in the cost of poor quality. First pass yield shows where units fail; putting a money value on the failures shows which step to fix first.
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