What Is Bitcoin’s Stock-to-Flow Model?

Stock-to-flow is a mathematical model to quantify the scarcity of an asset. It has its roots in ancient commodities analysis, where it is applied to examine how trends in supply determine price in the future. What is attempted here is to place an asset's current stock (the amount on hand currently) into context against its flow (the new supply that comes into the market annually).

Mathematically, the stock-to-flow ratio is a gauge of how long it would take at current production rate to produce the current stock. Scarcer and more valuable, historically speaking, are assets with higher stock-to-flow ratios. Gold and silver, for example - due to their relatively limited annual output in relation to their total reserves - have high stock-to-flow ratios and, as such, are good stores of value.

Applied to cryptocurrencies, the model provides us with a means of estimating the effect of scarcity of supply on market price. The method came into international focus when pseudonymous analyst PlanB originally suggested the stock-to-flow BTC model, projecting the idea onto Bitcoin's well-established schedule of supply. Since then, the term BTC stock to flow was included in the very heart of arguments over the valuation of Bitcoin, affecting institutional investors and retail speculators.

How Does the Stock-to-Flow Bitcoin Model Forecast Bitcoin's Price?

The stock-to-flow BTC model is based on the theory that value comes from scarcity. By measuring the finite amount of Bitcoin and comparing it to the rate at which new ones are being produced, the model calculates how market scarcity might affect long-term price action. In essence, the more time passes and the fewer new coins are produced annually (flow) while the supply of the existing coins increases slowly (stock), the scarcer Bitcoin becomes - and, in theory, the more valuable.

Key Principles of the BTC Stock-to-Flow Model

• Predictable Supply Schedule. The monetary policy of Bitcoin is hardcoded within its blockchain. The mechanism - a halving - that reduces new Bitcoin output in a planned manner to make BTC scarcer is halving of the block reward every 210,000 blocks (or approximately every four years).

• Scarcity and Valuation. As the stream of Bitcoin is reduced, its stock-to-flow rises. The larger the ratio, the longer it would take to produce as much as there is available, similar to decades to double the world's amount of gold by mining it. This effect of scarcity has always come with increased market valuations.

• Historical Price Correlation. Plotted on the BTC stock to flow, each halving period displays a pattern:

• Following the 2012 halving, the price of Bitcoin increased from about $12 to more than $1,000.

• Following the 2016 halving, it increased from about $650 to about $20,000.

• Following the 2020 halving, BTC increased from about $8,500 to more than $60,000 in 2021.

• Market Psychology and Expectancy. Investors like to project these points of halving, thereby creating more demand before ever experiencing scarcity. This is a part of a self-reinforcing cycle in which the stock-to-flow BTC model not only shows scarcity but also helps shape sentiment in the market.

• Mathematical Projection. PlanB's model is based on a logarithmic regression curve of the stock-to-flow ratio against the market cap of Bitcoin. The correlation has had a steady long-term trend, suggesting scarcity is that which explains most of the price movement of Bitcoin.

Although the model is far from ideal, it has provided a compelling story for long-term investors by connecting Bitcoin's algorithmically derived scarcity with its macroeconomic patterns of valuation. 

Does Bitcoin Have a High Stock-to-Flow Ratio?

Yes, Bitcoin boasts one of the strongest stock-to-flow ratios of any physical and virtual asset, and the stock-to-flow ratio grows as time passes because it has a halving mechanism. The stock-to-flow ratio is a metric of scarcity: the larger the value, the more difficult it is to inflate the supply of an asset.

Based on the latest BTC stock to flow ratio (after the 2024 halving), Bitcoin's S2F value is calculated to be around 112, meaning it would take around 112 years of the current output of mines to double the current supply of Bitcoins. This is similar to, if not higher than, gold - traditionally the measure of scarcity.

Most Important Factors Behind Bitcoin's High Stock-to-Flow Ratio

• Fixed Supply Cap. The total supply of Bitcoin is capped at 21 million coins and forms one of the pillars of its economic design. No central body can augment its supply, as opposed to fiat currency, ensuring perpetual scarcity in the long term.

• Halving Events. Every four years, Bitcoin's block reward halves:

• 2009: 50 BTC per block

• 2012: 25 BTC

• 2016: 12.5 BTC

• 2020: 6.25 BTC

• 2024: 3.125 BTC

Each cut decreases the flow - the amount of new coins entering circulation - and thus increases the BTC stock-to-flow ratio.

• Deflationary Issuance Model. The declining flow causes Bitcoin's supply of new money to diminish exponentially with time. This gradual inflation is orders of magnitude apart from fiat systems, where unlimited money can be printed by central banks, watered down by currency.

• Market Implications. High S2F ratio assets like Bitcoin or gold have traditionally been considered good stores of value. High ratio signifies durability, predictability, and inflation resistance - all of which are appealing to long-term investors and institutions.

• Comparison with Other Assets:

• Silver: S2F ratio ~20

• Gold: S2F ratio ~60-70

• Bitcoin (2024): S2F ratio ~112

This disparity highlights why others dub Bitcoin "digital gold" - it pairs scarcity with mobility and verifiability.

Since each halving cuts Bitcoin's rate of issuance in half, its stock-to-flow BTC model shows the ratio will increase even more, reinforcing the notion of Bitcoin as progressively scarce.

What Is the Stock-to-Flow Formula for Bitcoin?

The formula stock-to-flow is easy but very influential in its application. It computes scarcity as current supply (stock) of an asset divided by yearly production (flow).

For Bitcoin, it is written as:

Stock-to-Flow Ratio (S2F) = Total Bitcoins in Circulation / Bitcoins Mined per Year

This equation determines the number of years it would take, at this rate of production, to produce an amount equal to the amount that is currently in supply.

Example: Computing the BTC Stock-to-Flow Ratio

With approximate post-2024 halving figures, let's illustrate:

• Total BTC in supply (Stock): ~19.7 million BTC

• New BTC mined per annum (Flow): ~164,000 BTC

S2F=19,700,000​/164,000≈120

What this implies is that at the rate at which it is currently being mined, it would take around 120 years to double the circulating supply of Bitcoins.

How the Formula Binds in the BTC Stock-to-Flow Model

PlanB's stock to flow BTC model is not just a simple ratio equation - it uses the S2F figure in a regression model to make estimates of future levels of price. The formula for projecting price (in log scale) is:

ln(Price)=a+b×ln(S2F)

Where:

a and b are constants of regression from past data.

The use of the logarithmic scale makes it easy to project Bitcoin's exponential increase relative to its growing scarcity.

Key Takeaways from the Formula

1. Predictable Scarcity. Since Bitcoin's supply schedule is open and known, its S2F ratio can be predicted decades from now - something that cannot be done with traditional assets.

2. Correlation with Market Cycles. Historically, the price of Bitcoin in the market has tracked the BTC stock to flow chart remarkably closely, particularly following each halving. The correlation verifies that scarcity - as embodied by S2F - is an ongoing strong driver of value.

3. Dynamic Flow Reduction. Each halving doubles the ratio (as flow decreases by half), making Bitcoin increasingly exponentially scarce. It is a mechanism built into the core of the PlanB stock to flow BTC model, which synchronizes each halving cycle with big bull runs.

4. Weaknesses of the Formula. Although the model correctly balances supply-side dynamics, it fails to fully represent changes in demand, macroeconomic readjustments, or sentiment. Prices may diverge when externalities catch up with scarcity effects.

Visualizing the Relationship: The BTC Stock-to-Flow Chart

The BTC stock to flow chart graphs the past prices of Bitcoin versus its S2F ratio on a log graph. It normally graphs:

• Halving events (as points of inflection),

• Futures price lines extrapolated based on the S2F ratio, and

• Actual price data that move around the predicted trendline.

Irrespective of the fluctuations, the long-term trend follows the manufactured Bitcoin scarcity and increasing adoption.

Understanding the Bitcoin Stock-to-Flow Model

The stock-to-flow framework for Bitcoin remains one of the most contentious and powerful metrics for valuing it in the crypto world. In its ability to calculate scarcity through a simple ratio, it reconciles Bitcoin's mathematically pre-programmed supply schedule with its market price in the long term. Unlike traditional assets whose supply may be boosted based on demand, Bitcoin supply is pre-programmed mathematically, and analysts can now forecast its stock-to-flow BTC ratio decades ahead with high accuracy.

The PlanB stock to flow BTC model has delivered a structural means of viewing how Bitcoin's price moves within each halving cycle. The model in the past has exhibited a positive relationship of growing scarcity and rising price - but short-term market declines through speculation, macroeconomic, or liquidity cycles are usual.

Why the BTC Stock-to-Flow Model Matters

1. It Offers a Quantitative Framework for Valuation. The BTC stock to flow model provides investors with a real metric by which they can gauge Bitcoin scarcity - something old-fashioned market analysis tends to ignore. By keeping Bitcoin in its digital form, the model allows investors to evaluate long-term potential without day-to-day price swings.

2. It Substantiates the "Digital Gold" Narrative of Bitcoin. With every halving, Bitcoin's stock-to-flow ratio increases nearer to gold's, cementing it as a deflationary, value-storing asset more. In this metaphor, institutional acceptability and investor sentiment are encouraged, and BTC becomes an acceptable store of value among contemporary portfolios.

3. It Provides a Long-Term View. Though short-term volatility could diverge from expectations, the BTC stock to flow chart always shows how Bitcoin's algorithmic scarcity underpins its price cycles. The model's strength lies in its long-term orientation, focusing on underlying supply drivers as opposed to market noise.

Current BTC Stock-to-Flow Outlook

In the prevailing market cycle, the stock-to-flow ratio of Bitcoin is approximately 110-120, even tighter than that of gold. Post-halving in 2024, the model estimates an S2F-based range between $100,000 and $150,000 over the next couple of years - provided that historical correlations remain in place. That being said, the model is a theoretical rule and not a certainty indicator. Macro-economic changes, variability in demand, and regulatory changes can have gigantic impacts on real prices.

Criticism and Shortcomings

While the BTC stock to flow model has been helpful in illustrating Bitcoin scarcity, critics identify some deficiencies:

• Oversimplification: Demand is assumed to remain constant, something that will not occur in dynamic markets.

• External Variables: The cycle of the economy, geopolitics, and investor sentiment are typically variables that disrupt model predictions.

• Statistical Validity: In the opinion of some analysts, the correlation between stock-to-flow and price does not imply causality.

Despite those criticisms, the stock to flow model BTC continues to be one of the pillars of macro Bitcoin analysis, providing a coherent framework by which to approach its distinct monetary architecture.