A combination of intrinsic viscosity, sedimentation, and diffusion measurements is performed to characterize the structures of single-walled carbon nanotubes (SWCNTs) in dilute dispersion. It allows quantifying the bulk averaged length (L), diameter (d), molecular mass (M), and density (rho) as well as the surfactant adsorption for SWCNTs. With this approach applied to the SWCNTs processed by sonication, a novel Mark-Houwink-Sakurada equation, [eta](c) = 1.17M(0.33) is recovered. The less than 0.5 exponent is a result of the power-law relationship d proportional to L-0.62 caused by the concurrently occurred cutting and exfoliation of SWCNT bundles in the sonication process. An in-depth analysis of the experimentally acquired d and rho enables a quantification of sodium dodecylbenzenesulfonate (SDBS adsorption on SWCNTs to reveal the curvature effect) on the surface coverage of surfactant adsorption.