We analyzed the crop coefficient (Kc) of Pinus taeda within different planting densities in order to understand the effect of density population over the maximum water consumption, which will help us to improve its general values presented in the literature. The soil water balance was carried out over a year in a six years-old commercial pine forest in Southern Brazil. Soil water content was measured at different depths and Kc was estimated by the well-known ETc/ETo ratio, and by an alternative method based on wind speed, relative humidity, and plant height. The treatments consisted of different tree cover proportions: T100 (100% cover – standard planting cover, spacing 2.0 x 3.0 m – 1667 trees ha-1), T75 (75% cover), T50 (50% cover), T25 (25% cover), and T0 (no cover – clearcutting).  Analysis of variance was carried out with Tukey's test at 1% of probability. Tree cover did not affect the Kc for Pinus taeda. However, we observed significant lower Kc under full cover. As opposed to the recommended value for pine (Kc = 1), our results indicated average Kc equal to 2.12 in subtropical humid climate type. However, it was not possible to estimate a satisfactory value of Kc from climatic variables for the subtropical humid climate type.