What we see in the request, is nothing more than a Sturgess formula, which used to determine the number of groups (intervals) on which amount it is necessary to beat the input data in the histogram. There are other formulas, and on this occasion I wrote an article Determination of the number of groups in histogram generation
Looking at this article with a fresh look after 11 months from the time it was written, I realized what was missing. And the calculator is missing, which builds histogram directly from the data inputted (or imported) by the user. Naturally, while breaking data into intervals according to any of the formulas described in Determination of the number of groups in histogram generation.
Below, in fact, such a calculator - enter the data (clear that default data - it's only for illustration), select the method of grouping and calculator will build a histogram