© The Author 2014. Published by Oxford University Press on behalf of the Cambridge Political Economy Society. All rights reserved.This article is primarily concerned with a comparison of two different interpretations of the monetary equivalent of labour time (MELT), which is an essential category for the calculation of Marxian labour values. Beginning with a brief recap of these interpretations-temporal single system interpretation (TSSI) and the new interpretation (NI) of Duménil and Foley-the article emphasises the theoretical advantage of the TSS. Subsequently it refers to the second volume of Marx's Capital to highlight the fundamental role of the concept of turnover in Marxian value theory and argues that for the calculation of the MELT, the appropriate level of abstraction should be the turnover of social capital rather than annual statistics. At that point, the article attempts to show theoretically and mathematically that whenever empirical calculations are made on the basis of social turnover data, the MELT of TSSI essentially converges to the MELT of the NI. However, the article also notes that this convergence cannot be interpreted as a substantial equivalence of these different theoretical approaches.