Changing market demand and increasing environmental regulations challenge the refining industry to shift crude slates and reconfigure production processes while reducing emissions. Yet sellers and buyers remain unaware of the carbon footprint of individual marketable networks, and each crude oil has different specifications and is processed in different destination markets. Here we show the global refining carbon intensity at country level and crude level are 13.9–62.1 kg of CO2-equivalent (CO2e) per barrel and 10.1–72.1 kgCO2e per barrel, respectively, with a volume-weighted average of 40.7 kgCO2e per barrel (equivalent to 7.3 gCO2e MJ−1) and energy use of 606 MJ per barrel. We used bottom-up engineering-based refinery modelling on crude oils representing 93% of 2015 global refining throughput. On the basis of projected oil consumption under 2 °C scenarios, the industry could save 56–79 GtCO2e to 2100 by targeting primary emission sources. These results provide guidance on climate-sensitive refining choices and future investment in emissions mitigation technologies. The carbon footprint of oil refining differs depending on crude oil quality and refinery configuration. Analysis of global oil refining in 2015 shows refining carbon intensity at crude, refinery and country levels and highlights potential for emissions reductions.