Copper is vital to modern life and has an often-irreplaceable role in everyday infrastructure and technology. However, while the planet’s Cu endowment is finite, global Cu production continued to increase over the past century—a growth that has been matched by significant growth in estimated Cu mineral reserves and mineral resources. Here, we present a study of 2015 global Cu resources and reserves, updated from a previous paper (Mudd et al., 2013a) that outlined global Cu resources for 2010. The 2015 global Cu resource database consists of 2,301 deposits, of which 1,284 have code-based resources and 1,017 have noncode-based resources, with a further 403 of these projects having code-based reserves and a further four having noncode-based reserves. All mineral deposit types within the database have recorded an increase in Cu resources between 2010 and 2015 (except one), although grades are often similar or slightly lower (by ~5%) or are significantly lower, depending on the mineral deposit type considered. Porphyry deposits still dominate global Cu resources and reserves, containing ~75% of the contained Cu in our database. Equally unsurprisingly, Chile dominates global Cu resources and reserves, followed by the United States and Peru. The resources within the database contain some 3,034.7 million tonnes (Mt) of Cu, up from the 1,861.3 Mt reported in our 2010 study, plus we report 640.9 Mt of Cu contained in reserves (included in resources). This is a significant increase, even if all noncode-based resources were removed (i.e., 2,489.4 Mt Cu in code-based projects). There are three main reasons for this increase. First, this study is more comprehensive, with an increase in deposit numbers (730 vs. 2,301). Second, there have been new discoveries made (or rather resources outlined) between 2010 and 2015. Third, a significant proportion of resources within the 2010 study have grown in size (by a mean value of 13%), often coincident with significant amounts of production. This highlights the approaches taken by mining companies that do not delineate entire mineral deposits, especially if the systems are not completely understood, but instead drill out parts of mineralized systems, putting these into production and then often using the revenue to expand resources and reserves. This needs to be factored in when researchers are considering global metal resources, as using snapshots of resource data without considering they will most likely grow over time can often lead to erroneous conclusions. Finally, our study presents key long-term trends in Cu production as well as relationships between production, reserves, and resources. Overall, this study demonstrates that Cu resources continue to grow over time coincident with production, again suggesting that although discovery is important, the other factors that control the conversion of resources to reserves to production (e.g., mineralogic, environmental, political, logistical, and economical) are even more influential in terms of the future supply of Cu.