Using a modified version of Köhler’s method, recent research has found that in 2015 drain from the South through unequal exchange amounted to $2.1 trillion (constant 2011 dollars), represented in Northern prices (Hickel et al., 2021). Köhler’s proxy approach is limited in several respects, however. It relies on PPP figures that do not adequately account for the comparatively high prices of Northern exports; it relies on GDP figures that are affected by the low prices of imports from the South; and it compares Southern exports to prices across whole economies, rather than to those of only traded goods. All of this leads to underestimating the scale of drain (see Hickel et al., 2021).