The number-weighted particle size distributions are difficult to be estimated experimentally. This study offers a simple conversion method to convert mass-weighted distributions to their number-weighted equivalents. Besides, the number-weighted equivalents of the Gates-Gaudin-Schuhmann, Gaudin-Meloy, Pareto, and Rosin-Rammler distributions were determined by the conversion method. The accuracy of the method was successfully confirmed on the artificial populations generated from the Gates-Gaudin-Schuhmann, Rosin-Rammler (Weibull), and Pareto distributions. However, the number-weighted equivalent of the Gaudin-Meloy distribution was found to be trivial. The results also indicate that the conversion method may be applied to a wide range of sieve size distributions that are truncated with upper and lower bounds. (C) 2020 Elsevier B.V. All rights reserved.