DPU measures the average number of defects per every product unit. It’s found by dividing the total number of defects found by the number of units. In summary it is the average number of defects per unit. The ratio of defects to unit is the universal measure of quality. For example, if 30 units are produced and a total of 60 defects have been found, the DPU equals 2.

It is important to first understand the difference between two terms commonly used in connection with these performance measurement tools. The first is “defect.” The second is “defective.” (DPU uses defects)

  • DefectThis refers to a flaw or discrepancy in an operation or on an item where more than one flaw (defect) can be found. For example, a car is one finished unit in a process. A car also contains many different areas that are assembled to create a finished vehicle. Any of these areas – the seats, the dashboard, the engine, the exhaust system, etc. – could have defects. Given that, 10 finished cars could have more than 10 defects.
  • Defective: This refers to a decision made that an item is unacceptable, typically based on an accumulation of multiple defects. Again, using the car scenario, this means that 10 cars can have a maximum 10 defective units, because each car represents one unit.


D: number of Defects

U: number of Units




Six Sigma Material. “Defects per Unit (DPU)” Retrieved July 8, 2021, from https://www.six-sigma-material.com/defectsperunit.html

Admin. (2020, December). “Six Sigma Tools: DPU, DPMO, PPM and RTY.” Retrieved July 8, 2021, from https://www.sixsigmadaily.com/dpu-dpmo-ppm-and-rty/