Defects Per Unit Calculator
Work out defects per unit from your own defect and unit counts.
In short
Work out defects per unit from your own defect and unit counts.
Formula: DPU = Defects ÷ Units inspected
What this calculator does
One division. Defects per hundred units and units per defect are shown as restatements of the same figure.
Use it to turn Defects found, Units inspected 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
- 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.
Inputs used: Defects found, Units inspected.
Edge handling: Defects found is required.; Defects found cannot be negative.; Defects found must be no more than 1000000000000.; Units inspected is required.; Units inspected cannot be negative..
Worked example
37 defects across 500 units
- Start with Defects found: 37, Units inspected: 500.
- Apply the method: DPU = Defects ÷ Units inspected.
- 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
- Inputs outside the supported range are rejected rather than forced into a result.
- The result depends on the values you enter for this defects per unit 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, defect measures: defects per unit counts defects rather than defective units. See the source link on this page.
What kind of calculation is this?
Total defects counted divided by the number of units inspected. Check the formula, example, and limitations on this page before using the result for a real professional & industry decision.
What are its limits?
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.
How do I use the Defects Per Unit Calculator?
Enter the required values for Defects found, Units inspected. 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 Defects Per Unit Calculator use?
DPU = Defects ÷ Units inspected 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 Defects Per Unit 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
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.
Cite this page
Free Calculator. (2026, September 16). Defects Per Unit Calculator. https://freecalculator.tech/tools/defects-per-unit-calculator
"Defects Per Unit Calculator." Free Calculator, 16 Sept. 2026, https://freecalculator.tech/tools/defects-per-unit-calculator.
Defects Per Unit Calculator — Free Calculator, https://freecalculator.tech/tools/defects-per-unit-calculator
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