S2F (Stock-to-Flow)

A model that measures Bitcoin’s scarcity by comparing its existing supply (stock) to its annual issuance rate (flow), often used to predict price trends.

What is S2F (Stock-to-Flow)?

The Stock-to-Flow (S2F) model quantifies Bitcoin’s scarcity by dividing its total circulating supply (stock) by the annual amount of new Bitcoin issued through mining (flow).

As of 2025, Bitcoin’s circulating supply is approximately 19.92 million BTC, with an annual flow of about 164,250 BTC (post-2024 halving at 3.125 BTC per block, assuming 144 blocks daily). This yields an S2F ratio of roughly 121.3 (19.92 million ÷ 164,250), meaning it would take 121.3 years to produce the current stock at the current issuance rate. Higher S2F ratios indicate greater scarcity, akin to precious metals like gold (S2F ~60).

Introduced by pseudonymous analyst PlanB in 2019, the S2F model correlates Bitcoin’s price with its increasing scarcity, driven by halvings that reduce flow every four years. The model predicts significant price increases post-halving due to reduced supply growth; for instance, Bitcoin’s price surged to $120,000 by July 2025, aligning with S2F projections of $100,000–$150,000 post-2024 halving.

However, critics argue S2F oversimplifies market dynamics, ignoring demand fluctuations, regulatory impacts, or macroeconomic factors. Despite this, its historical accuracy—predicting peaks like $69,000 in 2021—has made it influential, though not definitive, in digital asset analysis.