Definition
The stock-to-flow ratio is a measure of scarcity that divides an asset's total existing supply (the stock) by the amount of new supply produced each year (the flow). The result can be read as the number of years of current production needed to recreate the entire existing supply. A high ratio means new production is small relative to what already exists, which is one way economists describe a "hard" or supply-resistant asset.
Origins in commodity analysis
The metric has long been used to compare commodities. Gold has a famously high stock-to-flow ratio because the vast quantity already mined dwarfs the modest amount added each year, which is part of why it historically served as sound money. Industrial commodities like copper have low ratios, because annual production is large relative to held stockpiles, so they are consumed rather than monetized.
Application to Bitcoin and its limits
Because Bitcoin's new issuance is fixed and halves roughly every four years, its stock-to-flow ratio rises over time and is sometimes compared to gold's. In 2019 the pseudonymous analyst PlanB published a model arguing that Bitcoin's price tracks its stock-to-flow ratio. That model is widely debated: critics note it considers only supply while ignoring demand, rests on limited data, and has diverged from actual prices in later periods. The stock-to-flow ratio remains a useful descriptive scarcity metric, but its value as a price-prediction tool is contested, and this entry takes no position on future prices.
The ratio underpins the broader idea of monetary hardness discussed in sound money and is one input people weigh when judging an asset as a store of value.
In Simple Terms
The stock-to-flow ratio is a measure of scarcity that divides an asset’s total existing supply (the stock) by the amount of new supply produced each…