The continued increase in the use of metals over the twentieth century has led to a substantial shift from geological resource base to metal stocks in society. Such a shift raises social, economic, and environmental issues that require quantifying the amount of stock of “metal capital” utilized by society. This report reviews the relevant literature on this topic. From a compilation of 54 studies, it is clear that a reasonably detailed picture of inuse stocks and in-use lifetimes exists for only five metals: aluminium, copper, iron, lead, and zinc, and in only two cases have spatial stock allocations been performed. Limited data suggest that per capita in-use stocks in more-developed countries typically exceed those in less-developed countries by factors of five to ten. Sparse but potentially useful in-use stock information exists for nineteen other metals. There is a little information on stocks in government repositories, and essentially none on stocks in “hibernation”, in tailings repositories, in industrial stockpiles, or in landfills, nor on typical in-use lifetimes for almost the entire periodic table of the elements. Outflows from in-use stocks, potentially useful for determining future rates of reuse, can currently be reliably estimated only for aluminium, copper, iron, and lead.