Conventional methods for measuring pore-size distribution (PSD), which are based on the capillary condensation (CC) and mercury intrusion porosimetry (MIP), are very sensitive to the numerical values of surface tension, sigma, of the corresponding liquid phase. However, it is generally accepted that sigma strongly depends on the curvature radius, r. Hence, PSD measuring seems unreliable if it does not involve the sigma (r) dependence. Experimental studies of the surface tension, sigma, for nuclei of liquids formed in the vapor upon homogeneous nucleation support the idea of no significant dependence of sigma on the curvature of the interface at the range of subnanometer radii.