For years the two most-cited quantitative Bitcoin models have been Stock-to-Flow (S2F) and the Power Law. They look superficially similar - both draw a rising line the price has tracked - but they rest on opposite assumptions and make very different long-term claims.
Stock-to-Flow: a supply-scarcity model
S2F prices Bitcoin from its scarcity. It divides the existing stock of coins by the annual new issuance (the "flow"), a ratio that jumps at each four-year halving as new supply is cut. S2F fit the early data strikingly well and, because issuance keeps falling, it implied an essentially open-ended, steeply exponential price path.
The Power Law: a demand-driven model
The Power Law makes no direct use of supply. It models price as a function of time and adoption - the network-effect story of users, addresses and hashrate compounding alongprice = a · t^b. Critically, it decelerates: percentage growth shrinks as Bitcoin matures, rather than continuing to explode.
Where they diverge
That difference is not academic. A supply-scarcity model with ever-tightening issuance projects prices that keep accelerating; a demand-and-time model projects growth that keeps slowing. Over a long horizon these paths separate dramatically. S2F's scarcity-driven predictions of continued exponential gains have not held up against subsequent price action, and the model has been widely criticized for treating a halving-driven ratio as if it caused price. The Power Law's decelerating shape has, so far, matched the realized data more closely.
What to take from the comparison
Neither model is a crystal ball. The Power Law's better track record does not make it destiny - it is still an extrapolation of a historical trend, sensitive to how the line is fit, and it could break. The useful takeaway is conceptual: be skeptical of models that promise unbounded acceleration, and prefer ones whose assumptions you can actually name. Use the live chart to see where price sits today, and the calculator to explore projections - as a starting point for thinking, not a recommendation.
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Educational content. Not financial advice.