Colonial extractive institutions are often blamed for current African underdevelopment. Yet, since colonial extraction is hard to quantify, the magnitude of this phenomenon remains unclear. In this paper, I use new archival data to estimate colonial extraction through trade, measured as the gap between prices that the monopsonistic French trading companies paid to African producers and prices that should have been paid in a counterfactual competitive market. The results show that African prices were only a small fraction of competitive prices, implying an annual loss of almost 2 percent of GDP during colonial rule.