How to read the estimate
These are ranges, not measurements. The calculator multiplies your counts by per-unit material figures from published characterization studies and industry averages for discarded equipment, and shows a low and high figure for each material. The hard-drive figures come from a recycling-oriented study of drives from desktop PCs and notebooks that reported magnet mass as a percentage of drive mass with a stated spread, and the neodymium content of the magnets themselves; the laptop figures come from a study that characterized discarded laptops whole; the smartphone figures are the Umicore/Hagelüken industry averages for the global handset stream. Both studied older, heavier equipment than a current fleet, so the laptop figures in particular — cobalt especially, which depends on battery chemistry — are shown as a range whose top is the study average and whose bottom is half of it. Treat the result as the right order of magnitude, not a bill of materials.
Why it is worth knowing anyway: the materials this tool counts are the ones the July 30, 2026 Defense Production Act determination named as recoverable critical materials essential to national defense, and the ones the Critical Minerals Recovery Field Guide traces from mine to rack. A retired fleet is a small, already-collected deposit of them. Whether it enters a documented domestic recovery chain or a closet is a disposition decision — and this tool is meant to make that decision feel as concrete as it is. The urban mining and rare earth elements entries in Straight Answers cover the vocabulary; the Battery & UPS Disposition Field Guide covers the hazardous stream the cobalt comes from.