Quality teams often report DHU and defect % as if they were the same. They are not.
DHU - Defects per Hundred Units
Formula: DHU = Total defects found ÷ Total pieces checked × 100
One garment can have several defects, so DHU counts every defect.
Defect % (defective %)
Formula: Defective % = Defective pieces ÷ Total pieces checked × 100
This counts pieces, no matter how many defects each piece has.
Example
You check 200 shirts. 12 shirts are defective; together they have 18 defects.
- DHU = 18 ÷ 200 × 100 = 9.0
- Defective % = 12 ÷ 200 × 100 = 6.0%
Which one to use
| Use | Better measure |
|---|---|
| Inline checks at the operator | DHU - shows every problem to fix |
| End-line and final audits | Defective % - how many pieces need repair |
| Comparing lines or operators | DHU, with the same checking method |
Making the number useful
- Record the defect type and operation, not just the count. A Pareto chart of defect types shows where to act first.
- Check at the same points and in the same way every day, or the numbers cannot be compared.
- React fast: a traffic light on the operator who creates defects stops the problem within the hour, not at the end of the day.
Tip: DHU falls when you prevent defects, but it also falls when checkers stop recording them. Audit the checkers from time to time.