Describing the breadth of a particle size distribution

Dauda Ladipo
(not verified)
Posted in: , on 12. Dec. 2002 - 19:57

I am looking for simple mathematical expressions for describing the spread or breadth of a particle size distribution. An example of what I am looking for is the "mid-fifty-breadth-ratio." (For the definition of this ratio, please see I would like to find other simple ways of describing a size distribution similar to the ratio mentioned above (in that it can be easily calculated). Any advice? Thanks in advance.

Paul A. Webb - Micromeritics, USA
(not verified)

Graphical Analyses

Posted on 12. Dec. 2002 - 08:55

I think what you are looking for are equations of the type used widely in the geosciences for extracting information from plotted distributions. Some references are:

Folk, R.L., and W.C. Ward, 1957, Brazos River Bar: A Study of the Significance of Grain-Size Parameters; J. Sediment. Petrology, 27:3-26.

Krumbein, W. C., Size-frequency distributions of sediments and the normal phi curve, J. Sed. Pet., 8, 84-90, 1983.

Robert E. Carver (edt.), 1971: Procedures in sedimentary petrology. Wiley-Interscience, A division of John Wiley and Sons, Inc., New York, London, Tokyo, 653 pp. ISBN 47113855 X.

Chapter 6 (pages 109-127): Mathematical Treatment of Size Distribution Data by Early F.McBride, University of Texas at Austin, Texas, US

Examples of these types of equations can be found at