DHU calculator (defects per hundred units)
Two inline-quality rates that are often confused: defects per hundred units and the percentage of pieces that are defective. Both use pieces inspected as the denominator; they differ in what they count.
How this is calculated
DHU = total defects ÷ pieces inspected × 100. Defective % = defective pieces ÷ pieces inspected × 100, where a defective piece is one with at least one defect, counted once. First-pass yield = 100 − defective %.
Worked example. 500 pieces inspected; 60 defects found on 45 pieces. DHU = 60 ÷ 500 × 100 = 12.00. Defective = 45 ÷ 500 × 100 = 9.00%, first-pass yield 91.00%, and 1.33 defects per defective piece.
DHU and defective percentage side by side
The same inspection can give a high DHU and a modest defective percentage, or the reverse, depending on how the defects are spread across garments. These examples show the two rates from the same counts.
| Pieces inspected | Defects found | Defective pieces | DHU | Defective % | Defects per defective piece |
|---|---|---|---|---|---|
| 100 | 5 | 5 | 5.0 | 5.0% | 1.00 |
| 100 | 10 | 5 | 10.0 | 5.0% | 2.00 |
| 100 | 30 | 10 | 30.0 | 10.0% | 3.00 |
| 200 | 40 | 25 | 20.0 | 12.5% | 1.60 |
| 500 | 60 | 45 | 12.0 | 9.0% | 1.33 |
Rows 1 and 2 have the same defective percentage (5%) but a DHU of 5 and 10: in the second the same five garments carry twice the defects, which means more repair time per garment. This is why a line is better judged on both.
Questions
- Which should I report, DHU or defective %?
- Both answer different questions. DHU counts defects and shows how much repair work the line is generating; defective % counts pieces and shows how many garments failed. A line fixing its worst operation may cut DHU sharply while defective % moves less.
- Can DHU be more than 100?
- Yes. 120 DHU means 120 defects per 100 pieces - several defects on some garments. Defective % cannot exceed 100.
- Is DHU the same as AQL?
- No. AQL is a sampling plan for accepting or rejecting a lot; DHU is a rate measured on whatever you inspected. Use the AQL calculator for lot acceptance.
- How do you calculate DHU in the garment industry?
- Count every defect found, divide by the number of garments inspected, and multiply by 100. If 60 defects are found in 500 garments, DHU is 60 ÷ 500 × 100 = 12.
- What does DHU stand for?
- Defects per Hundred Units. Some factories also write it as defects per hundred garments. It is a rate of defects, not a rate of defective garments.
- What is a good DHU?
- There is no single number. The target depends on the buyer, the style complexity and whether the inspection is inline or end-line. Use the figure in your buyer agreement or QC manual, and track the trend over time rather than one day.
- Should repaired garments be counted again?
- Count a garment in the first pass when it is first inspected. A garment repaired and re-inspected belongs to the repair count, not to a second first-pass inspection, or the first-pass yield will be understated.
Read the full guide
Sources & verification
DHU and percent defective are the standard attribute measures of inline and end-line inspection in apparel quality control; the definitions above are stated explicitly so they can be matched to your own QC manual. The worked example is recomputed in the automated tests.