Stock-to-Flow

The Stock-to-Flow chart plots Bitcoin's daily close against the model price predicted by the regression PlanB introduced in 2019. The model takes circulating supply (“stock”) divided by annual issuance (“flow”) and maps that ratio to a fitted price via a power-law relationship. The chart shows two lines: realised daily close, and the dashed S2F-implied model price computed from the live coefficients.

Today's S2F ratio is 121.9, yielding a model price of $218,171.27 against a spot of $78,199.03 — a residual of −64.2%. The current fit's coefficients are a = -1.3041, b = 2.8309, with R² = 0.9318. Spot refreshes a few times a day in the browser; the regression is refit nightly against the full daily-close history.

Inputs: the daily Bitcoin USD close history and a deterministic supply schedule keyed off the four canonical halvings (block heights 210,000 / 420,000 / 630,000 / 840,000 with subsidies 25 / 12.5 / 6.25 / 3.125 BTC respectively). For every day t:

stock(t) = circulating supply at day t
flow(t) = subsidy_t × 144 × 365
S2F(t) = stock(t) / flow(t)

The model is then a log-log OLS regression of price on S2F:

ln(price_i) = a + b · ln(S2F_i)

with implied model price price_model = exp(a) · S2F^b. PlanB's original 2019 fit reported b ≈ 3.3 and a ≈ 14.6 on a market-cap regression; our nightly refit publishes daily coefficients with the latest cycle included. Full derivation lives on the methodology page.

We use 144 blocks per day (the protocol target, not the realised ~147/day) for issuance, which trims roughly 2% off the absolute flow figure but preserves the doubling step at every halving. The S2F ratio is daily, not annualised — using a smoothed flow window would soften the step at each halving, which is the feature the model is built to highlight.

The single read on this chart is the residual: the gap between spot and model price. PlanB's regime thresholds were not formally codified, but the convention used in most replications is “extremely undervalued” below −50%, “fair value” within ±25%, and “extremely overvalued” above +100%. By that convention today's residual is in the extremely undervalued regime. The bands below carry the historical context.

Sampling the canonical cycle anchors against today's fit shows the model's behaviour across cycles. The 2013 and 2017 tops printed above the model; the 2018 cycle low printed near it. The 2021 tops are the inflection point — both the April $64,863 peak and the November $68,789 ATH printed sharply below a model that, with S2F at the post-halving step of ≈ 56, was implying values well above $100,000. The 2022 trough at $15,587 represents the model's worst failure on the record, with a residual near −94%.

For the two years following PlanB's March 2019 publication, S2F's model line and Bitcoin's realised price moved in close lockstep. PlanB explicitly forecast in the original piece: “The predicted market value for bitcoin after May 2020 halving is $1trn, which translates in a bitcoin price of $55,000” (Medium, 22 Mar 2019). Bitcoin reached $55,000 in late February 2021, broadly on schedule. PlanB then followed with the “Stock-to-Flow Cross-Asset” (S2FX) variant in 2020, which set higher post-2020 average targets.

What happened next is the model's defining failure. With S2F stepping to ≈ 56 after the May 2020 halving, the original regression implied a model price near $235,000. The realised April 2021 peak was $64,863. The realised November 2021 ATH was $68,789. The 2022 cycle trough was $15,587 — a residual of roughly −94% against the same model. PlanB's later S2FX variant fared even worse on that metric, with a stated “average price” for the 2020–2024 era of $288,000 against a realised average closer to $40,000.

The model has not recovered. Even the 2024 pre-halving high of $73,738 sits well below the model's pre-2024 implied value of around $100,000. The 2024 halving stepped S2F from ≈ 56 to ≈ 119, which under the original regression implies a forward model price above $1.5 million — the chart's largest residual on record. It is also the reason most thoughtful operators no longer treat the model as a price target.

Stock-to-Flow has attracted heavier econometric critique than any other mainstream Bitcoin valuation model. The technical objections were published before the model began breaking from price, and the data since has borne them out.

Nico Cordeiro (Strix Leviathan), 30 June 2020. “A Chameleon Model — Why Bitcoin's Stock-to-Flow Model is Fatally Flawed” (Strix Leviathan). Cordeiro's central claim: “The model's accuracy will likely be about as successful at forecasting Bitcoin's future price as the astrological models of the past.” The structural critique — that S2F's flow term is a step function of time, so any model regressing price against it is implicitly regressing price against time — has aged exceptionally well.

Level39 (via Harold Christopher Burger, 27 March 2022). Burger's “What's up with S2F?” (hcburger.com) catalogues the strongest mathematical critique to date — the “Stock is a function of Stock” framing originally posted by the pseudonymous Level39 — that the regression is structurally circular and that adjusting for the look-ahead drops R² toward zero. Burger himself, the author of the power-law corridor, runs a separate diminishing-returns critique: S2F predicts roughly equal-magnitude rallies from each successive halving, while the empirical data shows the opposite (each cycle's peak multiple shrinks).

Eric Wall's catalogue, 1 July 2020. “A list of the greatest blows to the S2F model” (Medium) catalogues the formal critiques: Sebastian Kripfganz's cointegration analysis (no statistical evidence for the relationship); Marcel Burger's spurious-regression walkthrough; and Nick Emblow's BTConometrics work showing the S2F correlation is “entirely spurious.” Emblow's pseudonym is a play on “Bitcoin econometrics,” and his S2F work was published under btconometrics.com — an independent site, often miscredited to institutional analytics shops in secondary sources.

For a dollar-cost-averaging investor. The S2F regime labels are mostly noise. Inflation-style scarcity arguments are useful as a long-run framing of Bitcoin's monetary properties, but the specific regression shown here has not forecast forward returns since 2020. Treat the chart as historical context, not operating guidance.

For a cycle-timing trader. Use the residual as a cross-check — a “model says −94%” print at the 2022 trough was, in retrospect, an extreme buy signal whether the model itself works or not. But do not size off the model price. Pair the chart with at least two of the Power-Law Corridor, the Rainbow, and the 200-week MA; S2F's residual is most useful as one column in a panel.

For a researcher. The S2F series and the model line are reproducible from the daily-close history plus the halving schedule. Coefficients refit nightly; the regression form, the 144-blocks-per-day convention, and the cointegration caveats are documented on the methodology page.

The 2021 overshoot is the model's defining failure. Documented in § 05 above: against a model price of roughly $235,000 at S2F ≈ 56, realised cycle peaks reached $64,863 (April 2021) and $68,789 (November 2021). The 2022 trough at $15,587 was a residual near −94%. The 2024 pre-halving high of $73,738 sat below the model's same pre-2024 implied value of around $100,000. Four consecutive cycle-anchor prints below the model is the empirical refutation; no narrative dressing covers it.

The regression is mathematically circular. Stock and flow are both functions of time (cumulative issuance and current-block-subsidy respectively), so the regression of price on S2F is nearly a regression of price on time with extra steps. The high R² is structural, not predictive. Burger's 2022 walkthrough at hcburger.com catalogues the Level39 framing of this circularity (“Stock is a function of Stock”) and shows the adjusted R² collapses toward zero. Cordeiro's June 2020 critique made the same point with a different methodology and arrived at the same conclusion.

Scarcity does not deterministically set price. S2F assumes the market is a pure scarcity-pricing engine — that doubling the stock-to-flow ratio at every halving deterministically translates to a multi-fold price step. That mechanism plausibly applies to gold and silver, where industrial demand is large and supply is the swing variable. Bitcoin's demand curve is dominated by speculative and institutional flows, not by industrial consumption; supply changes are well-known years in advance, so the market's price response to a halving is forward-discounted. The 2024 cycle has played out consistently with that “halving-priced-in” framing. Treat S2F as a historical curiosity and a cautionary tale, not as a forecast.

Canonical questions from Google's “People also ask” block for bitcoin stock-to-flow, answered against the data on this page.