As global health organizations and national governments tout "breast is best," the value of human milk is being calculated - and profited from - in increasingly diverse forms. In this paper I chart three of the major ways in which human milk is being economically valued: calculating breastfeeding as a contribution to a country's GDP; buying and selling human milk to hospitals for profit; and manufacturing key components of human milk and the infant gut. In exploring these bioeconomies, I draw together two approaches to biocapital not often put into conversation with one another: a focus on the micrological generative capacities of biological material, and attention to the macrological biopolitical governance of populations. I argue that juxtaposing these bioeconomies demonstrates key features of human milk biocapital: the multi-scalar workings of reproductive biopolitical valuation and governance; the human and more-than-human ecologies (and labours) on which biocapital depends; and the feminist geographical contestations that shape, and sometimes undermine, these valuations.