We discuss the reform of the voting rules at the heart of the governance of the IMF and World Bank (the BWIs) in terms of three principles that we suggest ought to be fundamental: simplicity, transparency and democratic legitimacy. By simplicity we mean that the rules should make sense in terms of the purposes of the BWI and be easy to understand. By transparency we mean that the rules mean what they appear to mean in the sense of leading to the same distribution of voting power as the institution’s designers intended. We show using voting power analysis that the inequality in the distribution of voting power among countries is greater than that of their voting weight. By democratic legitimacy, we consider whether we can reconcile weighted voting with democracy. Our conclusion is that the voting rules as they currently exist are far from satisfying any of these criteria and that recent reform proposals do not lead us to change this conclusion.