The Bitcoin stock-to-flow model is one of the most debated price frameworks in crypto. It's been called everything from "the most important chart in Bitcoin" to a flawed statistical artifact. The truth, as usual, is somewhere in between.
This post explains exactly how the model works, its track record through three halving cycles, and whether it still makes sense as a forecasting tool in 2026.
Bottom line: The S2F model has been directionally correct but numerically imprecise. It remains a useful framework for understanding Bitcoin's scarcity narrative — just not a reliable price prediction machine.
What Is the Stock-to-Flow Model?
Stock-to-flow (S2F) is a ratio used in commodity markets to measure scarcity. The formula is simple:
S2F = Stock ÷ Flow
- Stock = total existing supply of the asset
- Flow = annual new supply being produced
A higher ratio means more scarcity. Here's how Bitcoin compares to traditional stores of value:
| Asset | Stock (approx.) | Annual Flow | S2F Ratio | |-------|----------------|-------------|-----------| | Gold | ~6 billion oz | ~120 million oz | ~50 | | Silver | ~1.5 billion oz | ~27,000 tons | ~22 | | Bitcoin (pre-2024 halving) | ~19.4M BTC | ~328,500 BTC | ~59 | | Bitcoin (post-2024 halving) | ~19.7M BTC | ~164,250 BTC | ~120 |
After the 2024 halving, Bitcoin's S2F ratio surpassed gold's for the first time in history. According to the model, this should make Bitcoin the scarcest monetary asset on earth — and price should reflect that.
The Origin: PlanB's 2019 Paper
The Bitcoin S2F model was introduced in March 2019 by PlanB, a pseudonymous Dutch institutional investor. His original article, "Modeling Bitcoin Value with Scarcity," proposed that Bitcoin's market capitalization followed a power-law relationship with its S2F ratio.
The core claim: every time Bitcoin's S2F doubles (which happens at each halving), the market cap increases by roughly 10x.
PlanB fitted a regression line to Bitcoin's historical price data and found an R² of 0.95 — an extremely high correlation that generated enormous buzz in the Bitcoin community.
His model predicted that Bitcoin would reach somewhere between $55,000 and $100,000 after the 2020 halving. Bitcoin peaked near $69,000 in November 2021. Close enough to make headlines.
The S2FX Cross-Asset Model
In 2020, PlanB released an updated version: the Stock-to-Flow Cross-Asset (S2FX) model. Instead of tracking Bitcoin's price over time, S2FX clusters Bitcoin's market phases alongside gold and silver as comparables.
S2FX made a bolder prediction: Bitcoin would reach $288,000 during the 2020–2024 cycle.
That didn't happen. Bitcoin peaked at $69,000 in 2021, then fell back to $15,500 in 2022 during the FTX collapse. The S2FX model was widely criticized for its aggressive overshoot.
Bitcoin eventually broke $100,000 in December 2024, reaching an ATH near $108,000 in early 2025. The original S2F model's $55k–$100k range looks prophetic in hindsight for the 2020–2024 cycle. The S2FX $288k prediction does not.
How Each Halving Has Played Out
| Halving | Date | S2F Before | S2F After | Post-Halving Peak | Model Target | |---------|------|-----------|-----------|-------------------|-------------| | 1st | Nov 2012 | ~11 | ~22 | $1,100 (Dec 2013) | ~$10 | | 2nd | Jul 2016 | ~22 | ~44 | $19,800 (Dec 2017) | ~$1,000 | | 3rd | May 2020 | ~28 | ~56 | $69,000 (Nov 2021) | ~$55,000 | | 4th | Apr 2024 | ~56 | ~112 | ~$108,000 (Jan 2025) | ~$100,000–$500,000 |
The model has been directionally right — each halving cycle has produced higher prices. The magnitude, however, has diverged from the model's predictions in both directions.
What the Model Predicts for 2026 and Beyond
With a post-2024 halving S2F of approximately 120, the original power-law regression suggests a Bitcoin market cap target in the range of $5–10 trillion, implying a price of $250,000–$500,000 per BTC by the peak of this cycle.
The next halving in approximately 2028 will push S2F to ~240, theoretically implying another 10x increase in market cap.
You can explore these scenarios with our Bitcoin forecast calculator, which models multiple price frameworks including the Power Law.
That said, these figures represent a theoretical upper bound based on the model's regression — not a guarantee.
The Strongest Arguments For the S2F Model
1. It captures Bitcoin's defining feature: programmatic scarcity. No other asset in history has had supply mathematically capped and publicly verifiable. The halving mechanism is written into the protocol, not subject to political whims or mining economics in the same way gold is. S2F quantifies what makes Bitcoin uniquely scarce.
2. Three halvings, three bull markets. Correlation isn't causation, but the pattern is striking. Each of Bitcoin's four-year cycles has produced a new all-time high in the 12–18 months following a halving. Whether S2F caused this or simply describes it, the framework has been useful for timing expectations.
3. Institutional investors understand scarcity. When large institutions evaluate Bitcoin as "digital gold," they're implicitly using S2F logic — even if they don't call it that. MicroStrategy, BlackRock, and others cite Bitcoin's fixed supply cap as a core investment thesis.
4. It's self-reinforcing. As more investors know about the model, they position before halvings, which creates buying pressure that partially validates the model. Belief in a framework can make it more predictive.
The Strongest Arguments Against the S2F Model
1. It only models supply, not demand. A commodity with infinite scarcity and zero demand is worth nothing. S2F completely ignores demand drivers: regulatory risk, competing assets, technological obsolescence, adoption rates, and macro conditions. The 2022 bear market (driven by Fed rate hikes and FTX collapse) had nothing to do with supply.
2. Statistical criticism: spurious regression. Economists like Reginald Smith and researchers at the BIS have argued the S2F model suffers from non-stationarity — a statistical issue where two trending variables appear correlated simply because they both move in the same direction over time. In plain English: almost any two upward-trending variables will appear correlated, which doesn't mean one causes the other.
3. The model's own predictions have become increasingly imprecise. S2FX predicted $288k in the 2020–2024 cycle. Actual peak: $108k. That's a 62% miss on the downside. For a model claiming R² = 0.95, that's a significant deviation.
4. As S2F approaches infinity, the model breaks down. By 2140, all 21 million Bitcoin will be mined. Flow approaches zero. S2F approaches infinity. The model would imply an infinite price — which is obviously nonsensical. This suggests the model is curve-fitting historical data rather than capturing an underlying economic law.
5. Bitcoin increasingly trades on macro factors. Post-ETF approval (January 2024), Bitcoin's price action has become more correlated with equities and interest rate expectations. Institutional flows now dominate price discovery in ways that no scarcity model can predict.
Should You Use S2F to Make Investment Decisions?
Be cautious. Here's a balanced framework:
Use S2F to understand: Bitcoin's scarcity narrative and why each halving matters structurally. It's a useful mental model for understanding why Bitcoin's supply dynamics are unique.
Don't use S2F to time: Precise entry and exit points, or to predict specific price targets within a narrow band. The variance around S2F predictions is enormous — Bitcoin has been as far as 50%+ below the model's midline and 200%+ above it at different points.
Combine with other models: The Power Law model and on-chain metrics like MVRV ratio and realized price provide complementary perspectives. No single model should drive investment decisions.
Use a DCA strategy: Rather than trying to time a model-predicted peak, dollar-cost averaging removes the timing risk entirely. See our guide to dollar-cost averaging Bitcoin.
If you're ready to buy, bitcoinhodler.club has a directory of vetted exchanges to compare fees, withdrawal options, and security track records.
The Verdict on S2F in 2026
The stock-to-flow model is best understood as a narrative tool, not a precision instrument.
It correctly identifies that Bitcoin's supply halvings are the central structural event in each price cycle. It correctly predicts that scarcity increases over time. It has been directionally right across three halving cycles.
But it consistently overpredicts peak prices, ignores demand entirely, and has been challenged on statistical grounds by serious researchers. Treating it as gospel has led investors to expect $288k in 2021 and hold through a 77% drawdown.
The most honest summary: S2F tells a compelling story about why Bitcoin should be valuable. It's a much weaker tool for telling you exactly when or at what price.
For a broader look at where Bitcoin could go, check out our Bitcoin price prediction for 2026 and our 2030 forecast using multiple models.
Frequently Asked Questions
What does stock-to-flow mean for Bitcoin? Stock-to-flow measures Bitcoin's scarcity by dividing its total existing supply (stock) by the amount newly mined each year (flow). After the 2024 halving, Bitcoin's S2F ratio is approximately 120, making it more than twice as scarce as gold by this measure.
Who created the Bitcoin S2F model? The Bitcoin stock-to-flow model was created by PlanB, a pseudonymous Dutch institutional investor, in a March 2019 article titled "Modeling Bitcoin Value with Scarcity."
Has the S2F model been accurate? The original S2F model has been directionally accurate — predicting roughly $55,000–$100,000 for the 2020–2024 cycle, which Bitcoin achieved. The more aggressive S2FX model predicted $288,000, which Bitcoin has not reached. The model is better at directional trends than precise price targets.
What does a higher S2F ratio mean for Bitcoin's price? According to the model, a higher S2F ratio correlates with a higher price. After each halving doubles the S2F ratio, the model historically sees a 10x increase in market capitalization over the following cycle. However, these relationships have not been perfectly consistent.
Is stock-to-flow the best Bitcoin price model? No single model is "best." The Power Law model, on-chain metrics like MVRV, and fundamental demand analysis all provide valuable perspectives. Most serious analysts use multiple frameworks rather than relying on S2F alone.
What is Bitcoin's current stock-to-flow ratio? As of 2026, Bitcoin's S2F ratio is approximately 120 — more than double gold's ratio of roughly 50. This reflects the 2024 halving which cut the block reward from 6.25 BTC to 3.125 BTC.
What will Bitcoin's S2F be after the 2028 halving? After the 2028 halving, Bitcoin's block reward will drop to approximately 1.5625 BTC. With roughly 19.9 million BTC in circulation and only ~82,000 BTC mined annually, the S2F ratio will be approximately 240.