Free tool
Scrap rate calculator
Scrap rate is the share of the units you make that end up as scrap: units scrapped divided by total units made, times 100. Multiply the scrapped units by what each one cost and you have the cost of scrap. Track it by line, part and cause, because the total hides which problem costs the most.
Scrap rateequalsUnits scrapped divided by Units made × 100
Cost of scrapequalsUnits scrapped × Cost per scrapped unit
Saving at a target rateequals(Scrap rate − Target rate) × Units made × Cost per unit
Good and scrapped, in the period
Thrown away, not reworked
Material plus the work already in it
12 for a month, 52 for a week
Leave empty to skip the saving
Pre-filled with the worked example. Count scrap and units made over the same period, and use the same unit for both.
Scrap rate
2.50%
1,250 of 50,000 units; 48,750 good.
Scrap cost per period
$15,500
Scrapped units × cost per unit
Scrap cost per year
$186,000
Per period × periods per year
Units saved per period
500
At a 1.5% scrap rate
Saving per year
$74,400
Units saved × cost × periods
How to calculate it
Three numbers, and what to leave out
Units made and units scrapped are counted over the same period and in the same unit: pieces, kilograms or meters, but not a mix. Units made includes the scrapped ones.
Cost per scrapped unit is the material plus the labor and machine time already in the unit when it was scrapped. If the material can be recovered, subtract what you get back. A unit scrapped at final inspection costs more than one scrapped at the first operation.
Leave out rework: parts that are fixed and kept belong in first pass yield, not here. The full cost of getting it wrong also includes inspection, returns and warranty, which is the cost of poor quality.
Once you have the rate, sort the scrap by cause with a Pareto chart and take the top one into a root cause analysis. The target field then shows what that fix is worth, and the kaizen savings calculator adds what it costs to make.
Worked example
Illustrative numbers, not a benchmarkA line that made 50,000 units in a month and scrapped 1,250 of them. Each scrapped unit cost 12.40 in material and work. The team wants 1.5%.
- 1Scrap rate = 1,250 ÷ 50,000 = 2.5%.
- 2Cost of scrap = 1,250 × 12.40 = 15,500 a month, or 186,000 over 12 months.
- 3At 1.5%, scrapped units = 0.015 × 50,000 = 750, so 500 fewer a month.
- 4Saving = 500 × 12.40 = 6,200 a month, or 74,400 a year.
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<iframe src="https://www.theleansuite.com/tools/scrap-rate-calculator/embed" title="Scrap rate calculator by LeanSuite" width="100%" height="1100" style="border:0;max-width:1000px" loading="lazy" allow="clipboard-write"></iframe>
<p style="font:13px/1.4 sans-serif"><a href="https://www.theleansuite.com/tools/scrap-rate-calculator">Scrap rate calculator</a> by LeanSuite</p>How LeanSuite helps
LeanSuite's Quality Matrix pulls your defect data together, puts a dollar cost on each defect and shows engineering what to fix first.
See Cost of Poor QualityRead more
- Free template: Pareto chart template
- Free template: Root cause analysis template
- Scrap rate in the lean glossary
- First pass yield calculator
- Cost of poor quality calculator
- Scrap rate in the lean glossary
- Cost of Poor Quality: Calculation and Reduction Framework
- First Pass Yield: Definition, Calculation, and Improvement
FAQ
Scrap rate calculator: common questions
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