Resource efficiency is an instrumental mitigation option in the steel industry but, existing studies have failed to provide a global analysis of the sector's energy and material use. Despite the interactions between energy and materials in steelmaking, recent studies investigate each of these resources in isolation, providing only partial insight into resource efficiency. This study analyses the latest, most comprehensive resource data on the global steel industry and quantifies the savings associated with reducing this through energy- and material- saving measures. Three production routes are investigated for 2010, namely the blast furnace/basic oxygen furnace (ore-based); direct reduction/electric arc furnace; scrap-based electric arc furnace routes (secondary). The sector's resource efficiency - accounting for energy and materials - is expressed in exergy and measured at two levels, that of production routes and plants. The results show that the sector is 32.9% resource-efficient and that secondary steelmaking is twice as efficient (65.7%) as ore-based production (29.1%). Energy-saving options, such as the recovery of off-gases, can save about 4 EJ/year (exergy). Material- saving options, such as yield improvements, can deliver just under 1 EJ/year extra. A global shift from average ore-based production to best available operation can save up to 6.4 EJ/year; a 26% reduction in global exergy input to steelmaking. Shifting to secondary steelmaking can save 8 EJ/year, limited only by the need to still produce half of steel from ore in 2050. Resource efficiency, measured in exergy, provides stakeholders with an instrument that treats energy and material efficiency measures on an equal footing.