This article assesses the fundamental elements of national and international cartel sanctioning practices from a proportionality perspective under both retributive and consequentialist theories on punishment. It finds that the current framework of setting fines for international cartels fails to ensure proportionate overall punishment. This is due to two types of shortcomings. First, the amplification at an international level of the failure of national sanctioning methodologies to fully observe retributive or consequentialist proportionality principles. Second, the absence at an international level of an appropriate maximum limit on the level of punishment or any consideration of the overall proportionality of the overall punishment. Overcoming these shortcomings calls for not only the coordination of sanctions between authorities pursuing the same cartel, but also a serious reconsideration of the fundamental elements of national cartel fining methodologies. At the least, achieving overall proportionate punishment requires authorities to start considering the retributive and consequentialist objectives already achieved by fines imposed elsewhere for the same overall cartel conduct.