The Stock-to-Flow model, created by the anonymous analyst PlanB in 2019, was for a long time one of the most widely discussed attempts to mathematically value Bitcoin based on its scarcity. Its idea seemed convincing: the fewer new BTC entering the market relative to the existing supply, the higher the asset’s value should be. Each halving cuts the issuance of new coins in half, so the Stock-to-Flow ratio rises and, according to the model, the price of Bitcoin should increase significantly along with it.
Following the 2024 halving, Stock-to-Flow had an opportunity to undergo another serious test. By 2026, enough data had accumulated to assess how well it describes the current cycle. The answer turned out to be mixed. The idea that a reduction in supply affects Bitcoin’s long-term value retained a certain degree of logic, but S2F’s ability to accurately predict price levels once again came under serious question.
How Stock-to-Flow Works
Stock-to-Flow is calculated as the ratio of an asset’s existing stock to its annual production. The higher the ratio, the more difficult it is to rapidly increase supply. This is why the indicator has traditionally been applied to scarce commodities, particularly gold.
PlanB applied this logic to Bitcoin. BTC issuance is predetermined by the protocol, and approximately once every four years, the reward paid to miners is cut in half. Following the April 2024 halving, the block reward fell from 6.25 to 3.125 BTC, sharply reducing the volume of new coins entering circulation.
In 2026, Bitcoin’s S2F ratio stands at approximately 115–120, although the exact figure depends on the smoothing method used. By comparison, before the most recent halving, it was roughly half that level. This increase in scarcity is the fundamental basis of the model’s optimistic scenario. One current S2F tracker shows a modelled Bitcoin value of around $390,000, significantly above the actual market price.
What Happened After the 2024 Halving
After the halving, Bitcoin did indeed continue to rise and reached a new all-time high above $125,000 in October 2025. To a certain extent, this is consistent with the basic logic of Stock-to-Flow: the reduction in new issuance coincided with a new period of price growth.
However, a problem emerged afterwards. If S2F is used specifically as a price model rather than as a general concept of scarcity, Bitcoin should have been trading significantly higher. During 2026, BTC instead experienced a major correction and traded predominantly in the $60,000–$70,000 range over the summer. By early September, the price had recovered to approximately $78,000–$80,000, but it still remained far below the levels implied by most versions of Stock-to-Flow.
For example, one calculation for July 2026 showed a modelled value of around $209,000 compared with an actual price of approximately $66,000. The gap was more than 68%. Other implementations of S2F produced even higher calculated levels.
It was precisely this gap that became the main argument used by critics of the model during the current cycle.
Why the Model Once Again Diverged From the Actual Price
The main problem with Stock-to-Flow is that it focuses almost exclusively on Bitcoin’s supply, whereas price is determined by both supply and demand.
The halving does indeed reduce the number of new BTC received by miners, but it does not guarantee that investors will simultaneously increase their purchases. Demand depends on numerous factors that the S2F formula does not directly take into account:
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global US dollar liquidity and interest rates;
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demand from institutional investors and Bitcoin ETFs;
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the state of the stock market and investors’ attitude towards risk;
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cryptocurrency regulation;
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capital flows between Bitcoin, gold, equities and other assets;
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the behaviour of long-term holders and large BTC owners.
This became particularly evident in 2026. Bitcoin proved sensitive to expectations surrounding Federal Reserve decisions, inflation and conditions in global markets. For example, BTC’s recovery in September took place against the backdrop of changing expectations regarding US monetary policy.
Stock-to-Flow is virtually incapable of explaining such movements because monetary policy and investment demand are absent from its basic formula.
Does This Mean PlanB Has Abandoned S2F
No. PlanB continues to regard Stock-to-Flow as a useful model in 2026. Moreover, his own website still features S2F as a primary tool for analysing Bitcoin’s long-term value.
PlanB also does not consider the October 2025 all-time high to be the final peak of the current cycle. In the summer of 2026, he suggested that Bitcoin could even temporarily fall below the realised price of around $53,000 before still going on to establish a new high. His more optimistic scenario envisages BTC potentially moving to significantly higher levels, reaching as much as approximately $500,000 within the current cycle.
This is an important point when evaluating S2F. PlanB generally views the model not as a tool for predicting an exact price on a specific date, but as a long-term range around which Bitcoin can deviate significantly.
However, this is precisely where a methodological problem arises: the wider the permitted deviations and the more time the price is given to return to the modelled level, the more difficult it becomes to test whether the model is wrong.
The Main Problem With Stock-to-Flow Emerged in the Previous Cycle
The current gap is not the first. Back in 2021, Stock-to-Flow projected significantly higher prices than the market was able to deliver. At the time, PlanB published scenarios in which Bitcoin was expected to end certain months significantly above the actual levels. In November 2021, instead of the expected level of around $98,000, BTC ended the month at approximately $57,000, and in 2022 it fell below $16,000 altogether.
After that, it became more difficult to argue that there was a stable mathematical relationship between an increase in Stock-to-Flow and a specific market value of BTC.
The 2024–2026 cycle reinforced these doubts. The new halving did indeed coincide with another all-time high, but the scale of the increase was significantly smaller than the most optimistic interpretations of the model had suggested.
Where Stock-to-Flow Still Remains Useful
It would also be wrong to dismiss S2F entirely. The model illustrates one fundamental feature of Bitcoin very well: the predictable reduction in the rate of new issuance.
Unlike most financial assets, the supply of BTC can be calculated relatively accurately for decades into the future. If demand remains stable or increases, the reduction in the number of new coins does indeed create long-term pressure on supply.
Stock-to-Flow is therefore more useful when viewed not as a calculator of future prices, but as a scarcity model. It helps explain why halvings have economic significance and why Bitcoin over time becomes an asset with a very high ratio of existing supply to new issuance.
Problems arise when attempts are made to derive precise levels of $200,000, $500,000 or higher from this relationship.
Has S2F Survived the 2024–2026 Cycle
As of September 2026, it would be more accurate to say that Stock-to-Flow has partially survived another cycle as a concept, but has performed significantly worse as a price model.
Following the halving, Bitcoin did indeed establish a new all-time high, so the general idea of a relationship between scarcity and long-term growth does not appear to have been disproved. However, the actual BTC price once again diverged significantly from the values directly implied by S2F. With Bitcoin trading at around $78,000, some current versions of the model indicate a value of several hundred thousand dollars.
As a result, the main lesson of the current cycle is that Bitcoin’s scarcity matters, but scarcity alone is not enough to determine its price. The halving changes supply, but demand is shaped by interest rates, liquidity, institutional capital, investor behaviour and the state of the global economy.
PlanB still allows for the possibility that the remainder of the cycle will enable Bitcoin to move closer to the values indicated by S2F. With the next halving expected around 2028, there is indeed still time for such a scenario to unfold. However, the longer the actual price remains significantly below the modelled line, the more difficult it becomes to regard Stock-to-Flow as a standalone forecasting tool.
Therefore, in 2026, it is better to view S2F not as a formula capable of predicting Bitcoin’s future price, but as one way of measuring its programmable scarcity. In this role, PlanB’s model remains valid; however, when making practical decisions — for example, when an investor is planning to buy Bitcoin or exchange cryptocurrency — one should not rely solely on S2F. As a precise price forecast, the model’s results in the current cycle appear significantly less convincing so far.
