Water displacement (xylometry) was used to determine true volumes of 28 logs from Cilicica fir (Abies cilicica Carr.) and Brutian pine (Pinus brutia Ten.) trees ranging from 15 to 52 cm in diameter at breast height. Three methods were used with xylometry, measuring the increase in water level, the increase in weight of the xylometer or the decrease in weight of the object, and converting weight change to change in water volume. Traditional formulae (Huber, Smalian and Newton) and some recent methods and formulae (Bruce, overlapping bolts, Patterson-Doruska, the centroid and center of gravity) were used to estimate these volumes and the results were compared with the true values for both accuracy and precision. Comparison of these eight procedures for predicting log volumes of the two species tested showed that the centroid and center of gravity methods were less biased and provided better precision than other formulae and methods for estimating log volumes.