Using DPU, DPO, and DPMO to assess defects

DPU, DPO, and DPMO are metrics that express how your product or process is performing, based on the number of defects. Choosing the appropriate quality metric helps you assess performance against customer expectations. You can also develop project baselines and improvement goals, as well as communicate the level of conformance to your customers.

What is defects per unit (DPU)?

Defects per unit (DPU) is the number of defects in a sample divided by the number of units sampled.

Example of calculating DPU

Your printing business prints custom stationary orders. Each order is considered a unit. Fifty orders are randomly selected and inspected and the following defects are found.
  • Two orders are incomplete
  • One order is both damaged and incorrect (2 defects)
  • Three orders have typos
Six of the orders have problems and there are a total of 7 defects out of the 50 orders sampled; therefore DPU = 7/50 = 0.14. On average, this is your quality level and each unit of product on average contains this number of defects.

What is defects per opportunity (DPO)?

Defects per opportunity (DPO) is the number of defects in a sample divided by the total number of defect opportunities.

Example of calculating DPO

Each custom stationary order could have four defects - incorrect, typo, damaged, or incomplete. Therefore, each order has four opportunities. Fifty orders are randomly selected and inspected and the following defects are found.
  • Two orders are incomplete
  • One order is both damaged and incorrect (2 defects)
  • Three orders have typos
Six of the orders have problems, and there are a total of 7 defects out of the 200 opportunities (50 units * 4 opportunities / unit); therefore DPO = 7/200 = 0.035.

What is defects per million opportunities (DPMO)?

Defects per million opportunities (DPMO) is the number of defects in a sample divided by the total number of defect opportunities multiplied by 1 million. DPMO standardizes the number of defects at the opportunity level and is useful because you can compare processes with different complexities.

Example of calculating DPMO

Each custom stationary order could have four defects - incorrect, typo, damaged, or incomplete. Therefore, each order has four opportunities. Fifty orders are randomly selected and inspected and the following defects are found.
  • Two orders are incomplete
  • One order is both damaged and incorrect (2 defects)
  • Three orders have typos
There are a total of 7 defects out of the 200 opportunities. Therefore, DPO = 0.035 and DPMO = 0.035 * 1000000 = 35,000. If your process remains at this defect rate over the time it takes to produce 1,000,000 orders, it will generate 35,000 defects.
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