How do you make a six sigma calculator in Excel? Well it’s all really quite simple in excel….the calculator needs only a single formula to generate the sigma level for a process!!! You simply plug the number of opportunities & defects into an excel spreadsheet and calculate the sigma level by using NORMSINV (1 – defect/opportunities). You can download a copy of the six sigma calculator in excel here.

Before you use this calculator, a word of caution! There is a difference between the immediate sigma level as measured for a process right after making a process improvement and the one that a practitioner will typically report. The reason is that it is usually observed, that over a period of time, with more data being available, any future measurements of the standard deviation of a process would tend to be lower (and sigma levels tend to be higher). In the short term, we compensate for the non-availability of those additional data points by adding 1.5 to the measured sigma level so that the immediate and the long term sigma levels are not to far off. The number you arrive at by adding 1.5 to the immediate sigma level is then reported as the sigma level of a process.

Definitions of the data elements used as inputs by the six sigma calculator in Excel

Defect is defined as a non-conformance of a part or a process to the desired specification (shape, color, length, width, tolerance, hours, number of transactions).
Opportunities for defects are defined as the number of chances that a given part or a process could have resulted in a defect.

For some of my readers who might be wondering what this is all about…..well….the idea behind some of these and other forthcoming posts is to create a free repository of six sigma tools, all of course using Microsoft Excel. No subscription, no installation and all absolutely free. You may also want to download the six sigma table.

For the uninitiated, Six Sigma is a technique that seeks to improve the output of a process by identifying and eliminating the causes of defects (called errors) and variation in processes (standard deviation).