Uncertainties in quantitative estimates of the thermohaline circulation in any particular basin are large, partly due to large uncertainties in quantifying excess evaporation over precipitation and surface velocities. A single nondimensional parameter, <i>γ</i> ≡ <sup><i>q</i></sup>⁄<sub><i>h</i></sub> <sup><i>x</sup></i>⁄<sub><i>u</i></sub> is proposed to characterize the <q>strength</q> of the thermohaline circulation by combining the physical parameters of surface velocity (<i>u</i>), evaporation rate (<i>q</i>), mixed layer depth (<i>h</i>) and trajectory length (<i>x</i>). Values of <i>γ</i> can be estimated directly from cross-sections of salinity or seawater isotopic composition (<i>δ</i><sup>18</sup>O and <i>δD</i>). Estimates of <i>γ</i> in the Red Sea and the South-West Indian Ocean are 0.1 and 0.02, respectively, which implies that the thermohaline contribution to the circulation in the former is higher than in the latter. Once the value of <i>γ</i> has been determined in a particular basin, either <i>q</i> or <i>u</i> can be estimated from known values of the remaining parameters. In the studied basins such estimates are consistent with previous studies.