Scrap Rate Calculator
Work out the share of units started that had to be discarded.
What this calculator does
One division expressed as a percentage. Rework is shown separately and never added to scrap.
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
Worked example
96 units scrapped out of 4,800 started
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
Results depend entirely on the figures you enter and are rounded for display. They are for general information and education, not professional advice.
Reference: American Society for Quality — Process capability and defect rate measures
Last reviewed:
Common questions
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.
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