Scrap Rate Calculator
Work out the share of units started that had to be discarded.
In short
Work out the share of units started that had to be discarded.
Formula: Scrap rate = (Units scrapped ÷ Units started) × 100
What this calculator does
One division expressed as a percentage. Rework is shown separately and never added to scrap.
Use it to turn Units started, Units scrapped, Units reworked (optional) into a checked result you can compare, copy, or rerun with different assumptions.
The page shows the formula, a numeric worked example, and the assumptions that affect this professional & industry calculation.
Inputs and what they mean
- Units started
- — number value.
- Units scrapped
- — Units discarded because they cannot be reworked to specification..
- Units reworked (optional)
- — Optional. Leave at 0 to exclude it from the result. Shown separately; reworked units are not scrap..
How to use it
- Enter your own figures — the calculator never fills in a rate, price or benchmark for you.
- Press Calculate to see the result.
- Read the formula, variables, assumptions and source below the result before you rely on it.
Formula
Scrap rate = (Units scrapped ÷ Units started) × 100.
Inputs used: Units started, Units scrapped, Units reworked (optional).
Edge handling: Units started is required.; Units started cannot be negative.; Units started must be no more than 1000000000000.; Units scrapped is required.; Units scrapped cannot be negative..
Worked example
96 units scrapped out of 4,800 started
- Start with Units started: 4800, Units scrapped: 96, Units reworked (optional): 0.
- Apply the method: Scrap rate = (Units scrapped ÷ Units started) × 100.
- Rework is counted separately from scrap.
Reading the result
The headline figure is the main answer. Any breakdown underneath shows the parts that make it up, so you can check the working and see what changes when you adjust an input.
Limitations and assumptions
- Inputs outside the supported range are rejected rather than forced into a result.
- The result depends on the values you enter for this scrap rate calculator; it does not supply missing rates, rules, prices, dates, or assumptions for you.
Reference: American Society for Quality — Process capability and defect rate measures
Last reviewed:
Common questions
Where does this formula come from?
ASQ quality resources, waste measures: scrap counts units discarded, distinct from units reworked. See the source link on this page.
What kind of calculation is this?
Units discarded as a percentage of units started, with reworked units reported separately. Check the formula, example, and limitations on this page before using the result for a real professional & industry decision.
What are its limits?
A unit reworked and then scrapped should be counted once, as scrap; the calculator cannot detect double counting. Arithmetic over the counts entered — it cannot tell whether the inspection behind them was complete or consistent.
How do I use the Scrap Rate Calculator?
Enter the required values for Units started, Units scrapped, Units reworked (optional). The calculator applies the formula on this page and shows the main result with any supporting breakdown so you can check the arithmetic.
What formula does the Scrap Rate Calculator use?
Scrap rate = (Units scrapped ÷ Units started) × 100 The visible formula section above lists the calculation path and the edge cases the page handles, so the result can be checked without relying on the form alone. Check the formula, example, and limitations on this page before using the result for a real professional & industry decision.
Can the Scrap Rate Calculator be used for exact decisions?
Use it as a calculation aid, not as a substitute for checking the underlying rule, contract, policy, or professional advice that applies to your situation. When a result depends on local rules, personal details, prices, or dates, enter those values yourself and confirm them before acting.
Formula, source and verification
Units discarded as a percentage of units started, with reworked units reported separately.
The question it answers: What share of our output is discarded, and what share has to be put right?
The formula
Scrap rate = (Units scrapped ÷ Units started) × 100
- Sc — Units scrapped
- (count). Units discarded because they cannot be brought to specification.
- S — Units started
- (count). Units entering the process.
- R — Units reworked
- (count). Optional. Reported separately; rework is not scrap.
Units: Counts in; percentage out.
What kind of calculation this is
Deterministic formula. The same inputs always give the same answer. The maths is fixed and does not depend on judgement.
Method
One division expressed as a percentage. Rework is shown separately and never added to scrap.
Assumptions built into the result
- Mathematical: Scrapped units are counted once, at the point they are discarded.
Figures this calculator will never guess for you
- No benchmark, target or 'world class' value is supplied or implied; the result describes only the figures entered.
- No scrap cost or material value is inferred here — the Scrap Cost Calculator handles that separately.
Limitations
- A unit reworked and then scrapped should be counted once, as scrap; the calculator cannot detect double counting.
- Arithmetic over the counts entered — it cannot tell whether the inspection behind them was complete or consistent.
Source and version
- Standard or reference
- Scrap rate — ASQ (ASQ quality resources, waste measures: scrap counts units discarded, distinct from units reworked.)
- Published source
- American Society for Quality — Quality resources
- Formula version
- Version 1
- Verification
- Reviewed against the cited source on
- How much weight the source carries
- Standards or government
- Applies to
- Currency
- The result is a ratio or index, so it does not depend on currency.
Cite this page
Free Calculator. (2026, September 16). Scrap Rate Calculator. https://freecalculator.tech/tools/scrap-rate-calculator
"Scrap Rate Calculator." Free Calculator, 16 Sept. 2026, https://freecalculator.tech/tools/scrap-rate-calculator.
Scrap Rate Calculator — Free Calculator, https://freecalculator.tech/tools/scrap-rate-calculator
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