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This study aimed to test probability density functions for the distribution of variables total height, transverse area and individual volume, considering three different class intervals. Data were obtained from the measurement of diameter (DBH) and total height and from estimation of the individual volume of 338 pine trees in a fragment of Mixed Ombrophylous Forest with an area of 15.24 ha, which is located in Jardim Botânico campus of UFPR, Curitiba-PR. Ten functions were fitted, including commonly used models for diameter distribution as well as other recently developed models applied to forest science. Selection criteria included Kolmogorov–Smirnov adherence test, standard error of estimate in percentage and adjusted coefficient of determination. Three class intervals were used as obtained by Sturges, Dixon & Kronmal, and Velleman criteria. The Normal function for variable height, and the Weber function for distribution of transverse area and individual volume, provided the best fit, considering the three class intervals adopted. The models fitted better for larger size class intervals as obtained by Sturges rule.