Wind power is often posed as a greenhouse gas emission mitigation option, yet from a global perspective, the constrained supplies of rare-earth metals required for large-scale offshore wind turbines seem increasingly likely to provide limits to offshore wind power and other rare-earth-metal applications in the coming years. A 2015 US Department of Energy study maps an ambitious roadmap for offshore wind power to be capable of meeting substantial US electric-generating capacity by 2050. Our study addresses the neodymium material requirements that would be needed. We find that regional differences in deployment schedules will result in complex patterns of new capacity additions occurring concomitantly with turbine retirements and replacement needs. These demands would total over 15.5 Gg (15.5 kt) of neodymium by 2050, of which 20% could potentially be avoided by circular usage from decommissioned turbines but only if recycling technologies are developed or, better still, magnets are designed for reuse. Because neodymium is deemed to be a ‘critical material’, these perspectives are vital information for the formation of policy related to wind-energy provisioning, to domestic production, and to the importation of the rare-earth elements that would be required.