Stock-to-Flow (S2F)

Stock-to-flow is the ratio of an asset's existing supply (stock) to its annual new production (flow). A high ratio means new supply barely dilutes holders. Gold's stock-to-flow is roughly 60, with over 200,000 tonnes above ground against a few thousand tonnes mined yearly. Bitcoin's exceeded 100 after the April 2024 halving cut issuance below one percent per year.

Why it matters

Stock-to-flow captures why some goods work as money and others fail. Commodities with low ratios, like copper or oil, see supply respond quickly to price, crushing any monetary premium; goods with high ratios, historically gold and silver, can absorb savings because producers cannot flood the market. The ratio became famous in bitcoin circles through a 2019 model by the pseudonymous analyst PlanB, which fit bitcoin's price to its stock-to-flow and projected steep post-halving gains. The model's specific price predictions overshot and it is widely criticized as statistically unsound, so the durable insight is the property itself, not the price targets.

In the gold vs bitcoin debate

Stock-to-flow is the metric on which the two assets converged and then crossed. Gold held the highest ratio of any monetary good for all of history until bitcoin's halvings pushed its ratio past gold's, and every future halving widens the gap. Gold advocates respond that a ratio is not a guarantee of demand, and that gold's ratio is backed by millennia of monetary use while bitcoin's is a promise only as old as its code. As a comparative lens rather than a price model, stock-to-flow remains one of the most useful single numbers in the debate.