How to use this calculator
- Enter or choose pieces inspected.
- Enter or choose defective pieces.
- Enter or choose total defects found.
- Enter or choose rejected pieces.
- The rejection rate updates as you type. Use Copy result or Share to keep it.
Method
Rejection % = Rejected ÷ Inspected × 100; Defective % = Defective ÷ Inspected × 100; DHU = Defects ÷ Inspected × 100
- Inspected
- pieces checked
- Defective
- pieces with one or more defects
- Defects
- every defect counted, so one piece can have several
- Rejected
- pieces that could not be repaired
Worked example
- Rejection = 8 ÷ 500 × 100 = 1.6%.
- Defective = 40 ÷ 500 × 100 = 8%.
- DHU = 52 ÷ 500 × 100 = 10.4.
- First-pass yield = (500 − 40) ÷ 500 = 92%.
Of 500 pieces, 1.6% were rejected, 8% needed repair and the line ran at 10.4 DHU.
What the result means
DHU is the best measure of process quality because it counts every defect; rejection rate measures the cost of defects that could not be repaired. Track both per line and per operation.
Assumptions and limits
- Rejected pieces are a subset of defective pieces.
- Results from a sample inspection only represent the lot if the sample was drawn randomly.
Questions
Can DHU be higher than 100?
Yes. Because one piece can carry several defects, DHU can exceed 100 even though defective % cannot.
What is an AQL inspection?
An acceptance sampling plan that decides from a sample whether to accept a whole lot. This calculator reports the rates you found; it does not apply an AQL table.