Defects Per Unit Calculator
Work out defects per unit from your own defect and unit counts.
What this calculator does
One division. Defects per hundred units and units per defect are shown as restatements of the same figure.
Inputs and what they mean
- Defects found
- — Total defects counted, not the number of defective units. One unit can carry several defects..
- Units inspected
- — number value.
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
DPU = Defects ÷ Units inspected
Worked example
37 defects across 500 units
Counts defects, not defective units, so the figure can be above one.
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
Total defects counted divided by the number of units inspected.
The question it answers: How much of our output is right first time, and how much survives every step?
The formula
DPU = Defects ÷ Units inspected
- D — Defects
- (count). Total defects found, not the number of defective units.
- U — Units inspected
- (count). Units examined in the sample or period.
Units: Counts in; defects per unit 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. Defects per hundred units and units per defect are shown as restatements of the same figure.
Assumptions built into the result
- Mathematical: A defect has been defined consistently for every unit inspected.
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 yield is inferred from defects per unit; no distributional assumption is applied.
Limitations
- Defects per unit is not a defective rate — a unit with three defects counts three times.
- Arithmetic over the counts entered — it cannot tell whether the inspection behind them was complete or consistent.
Source and version
- Standard or reference
- Defects per unit — ASQ (ASQ quality resources, defect measures: defects per unit counts defects rather than defective units.)
- 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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