Six Sigma Calculators – DPMO, DPM, Sample Size

DPMO – Defects Per Million opportunities

We have calculators developed in JavaScript as well as in Excel. You can play with them below or download for offline practice. DPMO is a measure of process performance. A defect happens when a product’s quality characteristic such as color, weight, size is not in conformance to the product’s specification.  Observed during an average production run,  defects per million opportunities is defined as the average number of defects per unit divided by the number of opportunities to make a defect on the product during that run normalized to one million. Defects per million opportunities (DPMO) is also known as nonconformities per million opportunities (NPMO). We calculate DPMO using the below formula:


DPMO = \frac{Defects\hspace{2mm}*\hspace{2mm}1000000}{Defect\hspace{2mm}Opportunities\hspace{2mm}Per\hspace{2mm}Unit\hspace{2mm}* \hspace{2mm}Number\hspace{2mm}Of\hspace{2mm}Opportunities}

DPMO Calculator

Number Of Defects:
Number Of Opportunities:
Number Of Defect Opportunities per Unit:
Click to Calculate DPMO:

Six Sigma:

DPM – Defects Per Million

We calculate DPM using the below formula:
 DPM = \frac{Defects\hspace{2mm}*\hspace{2mm}1,000,000}{Sample\hspace{2mm}Size}

DMP Calculator

Number Of Defects:
Sample Size:
Click to Calculate DPM:

Six Sigma:

Sample Size

Sample Size is calculated using the below formula:
Six Sigma Sample Size Formula

Where CI is the confidence Interval in decimal format. If the Confidence Interval is ±4% then use 0.04.
p is Percentage of the sample picking a choice, expressed in decimal.

Sample Size Calculation:  For a Confidence Level of 95%, which is the most commonly used Confidence Level by researchers, we use a p = 0.50 and  Z value = 1.96. A confidence level of 95% means that you are 95% certain about the outcome.

Sample Size Correction For finite Population

The above formula works for bigger populations. For smaller or finite populations, you need to correct the value obtained from the above using the below formula.
Sample Size Correction For finite Population Formula

Sample Size Calculator

Confidence Level: 95%
Confidence Interval:
Click to Calculate Sample Size:

Defect Metrics Calculators in Microsoft Excel Spreadsheet

Download free Six-Sigma Calculators for DPO, DPMO, Sample-Size in Excel

Further reading: SixSigma Daily DPMO, iSixSigma discussion on how to calculate DPMO and Sigma

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