The propagation velocity of ultrasonic waves from measurements in trees is numerically different from the velocity obtained from measurements in logs, even in freshly felled logs, and the latter velocity is better correlated with the quality of the wood. The differences can be explained by the basic and fundamental aspects of wave propagation; however, these aspects are difficult to consider in practical applications. Thus, the present study examined parameters that are more easily obtained in the field and considered to provide an equivalent log velocity based on living tree velocities. The results indicate that base logs are better correlated with the velocities measured in trees, because the measurement in trees is performed at the stem base. However, the inclusion of the diameter at breast height (DBH) can produce a model with the same prediction accuracy as that of logs obtained from the whole tree. The inclusion of the green density does not improve estimations of the velocity of logs using the velocity obtained for the tree. Considering that DBH is a parameter often used in forest management, this result can be useful for improving the accuracy of wood-quality predictions from acoustic trials in standing forests.