The chirality and diameter are found to simultaneously affect the solubility of SWCNTs. The solubility parameter of armchair SWCNTs is greater than that of zigzag SWCNTs, for a given diameter and length, except for very small diameters. The lower structural stability of the armchair SWCNTs leads to smaller molar volumes. Thus, the chirality of SWCNTs alters the structural stability and consequently the solubility parameter of the SWCNTs.