The accuracy of Pozyx is 10 cm in line-of-sight (LOS) conditions. In non-line-of-sight (NLOS) conditions, the accuracy tends to vary between 10 and 30 cm, depending on the material and density that is obstructing the signal.
The accuracy is not influenced by range nor is it influenced by the number of anchors you use, though a minimum of 4 anchors is required for 2D positioning. The use of at least 6 anchors placed at varying heights is recommended for 3D positioning. More anchors will increase the range and robustness of the system in case of obstruction.