How to use this calculator
- Enter all time values using the units shown.
- Use counts from the same production period.
- Select Calculate and review the main result plus supporting metrics.
- Change one assumption at a time to compare operating scenarios.
#2143 · Logistics & Manufacturing Tool
Assembly Line Yield Loss Calculator
Turn rejected or reworked output into a clear operational and cost estimate for the assembly line. Enter the total units produced, units passing on the first attempt, material value per failed unit, and average rework cost. The calculator separates first-pass yield, failed units, direct material exposure, and rework expense so teams can update assumptions without relying on a generic benchmark.
Calculator
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Formula
Failed units = total units − first-pass good units
Yield loss rate = failed units ÷ total units
Total quality-loss cost = failed units × (material value + rework cost)
Yield loss rate = failed units ÷ total units
Total quality-loss cost = failed units × (material value + rework cost)
What the result means
Failed units are items that did not pass on the first attempt. The cost result combines entered material exposure and rework cost; it is not an accounting write-off forecast.
Do not add rework cost to units that are scrapped unless the same units actually incur both costs. Adjust the inputs to match the plant's cost treatment.
Example calculation
From 1,000 total units and 950 first-pass good units, 50 units fail first pass and yield loss is 5%. At $4 material value and $2.50 rework per failed unit, the estimated total is $325.
Tips for better results
- Use a consistent start and stop boundary for every input.
- Separate planned stops from unplanned downtime.
- Use first-pass good units when quality losses must remain visible.
- Recalculate by product family when cycle times differ.
- Compare estimates with several representative runs before setting targets.
Frequently asked questions
Should planned downtime be included in this assembly line yield loss calculator?
Use the time boundary defined by the inputs: subtract planned excluded time where requested and keep all values within the same production period.
Can I use this calculator for multiple products on the same line?
Yes, but use a weighted or representative cycle only when the product mix is stable; separate runs are clearer when cycle times differ materially.
How should rework be treated in the assembly line yield loss calculator?
Count first-pass good output where the calculator requests good units, and track rework separately so repeated processing is not hidden.
Why does my calculated result differ from the line report?
Check time boundaries, unit conversions, whether micro-stops are included, and whether the report uses total units or first-pass good units.
Can this result be used for staffing or capacity planning?
It can support scenario planning, but validate the entered times and output assumptions against representative production data before making commitments.
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Variables and measurement boundaries
| Cost input | Applied to | Included result |
|---|---|---|
| Material value | Each failed unit | Material loss exposure |
| Rework cost | Each failed unit | Rework expense |