Stock-to-flow
Stock-to-Flow
Scarcity model vs reality, price coloured by halving distance.
PlanB's scarcity model (0.4 × S2F³, smoothed): each halving doubles stock-to-flow and steps the model up. Dot colour is days to the next halving — the scale on the right. The model has badly overshot since 2021 — shown as history, not endorsement.
How this is built
Scarcity model vs reality, price coloured by halving distance.
FormulaSF = stock / flow₁ᵧ; P̂ = e^a · SF^b
AuthorPlanB
CoinGeckoPrice, market caps, all-time highs and dominance.
Blockchain.comFull-history market price used to backfill the long charts.
mempool.spaceBlock height, fees and mining — powers the network figures.
The indicator is PlanB's published idea, and Perly claims no authorship of it. Perly draws the chart from the data of the providers listed above, and that data remains theirs.
How to read the stock-to-flow chart
Each dot is bitcoin's price on one day, on a logarithmic axis. The coral line is the stock-to-flow model: the price the model gives bitcoin's scarcity on that day. Where the dots sit above the line the price was above the model's value, and where they sit below it, under it.
The dots are coloured by the time that was left until the next halving, and the scale on the right reads the colour in days. Just after a halving they turn red; as the next one comes closer they cool through yellow and green to blue and deep purple. The dashed grey verticals are the halvings themselves, where the flow of new coins halves and the stock-to-flow ratio doubles — which is why the model line climbs steeply in the year after each one.
Hovering any day shows the price, the model's value and the days to the next halving, and the readout above gives today's price and model. There are no range chips on this chart; on a computer, drag across the plot to zoom and double-click to reset.
Price against the model at every cycle top and low
| When | BTC price | S2F model | Price ÷ model |
|---|---|---|---|
| Cycle low21 Nov 2011 | $2.30 | $5.66 | ×0.41 |
| Cycle top04 Dec 2013 | $1,137 | $232 | ×4.91 |
| Cycle low14 Jan 2015 | $172 | $337 | ×0.51 |
| Cycle top16 Dec 2017 | $19,280 | $5,384 | ×3.58 |
| Cycle low15 Dec 2018 | $3,232 | $6,090 | ×0.53 |
| Cycle top08 Nov 2021 | $67,562 | $64,284 | ×1.05 |
| Cycle low21 Nov 2022 | $15,760 | $68,028 | ×0.23 |
| High so far06 Oct 2025 | $124,740 | $617,845 | ×0.20 |
| Low so far30 Jun 2026 | $58,566 | $629,649 | ×0.09 |
| Latest20 Oct 2026 | $81,558 | $634,645 | ×0.13 |
How Perly computes the model
Stock is the number of bitcoin in existence. Perly counts it from the issuance schedule rather than from a feed: 144 blocks a day, and a reward of 50 bitcoin a block that halves at each halving, with the halvings on the days they actually happened. Flow is a year of new coins at that day's reward, 144 × 365 blocks' worth. Stock divided by flow is how many years of current production it would take to mine the existing supply again.
The model price is 0.4 × SF³, a simplified price form of the model, and the line is that value averaged over the 365 days up to each day. The averaging is why the line climbs through the year after a halving rather than jumping on the day: the raw value multiplies by eight when the ratio doubles.
Where it comes from
The pseudonymous analyst PlanB published the stock-to-flow model in March 2019, relating bitcoin's value to its scarcity with the ratio used for gold and silver: existing stock over yearly production. His fit was made on market value; the price form drawn here is a simplification of it, so this line will not match every other stock-to-flow chart to the dollar.
What the model has and has not done
From 2012 to 2021 the price swung around the model, above it at the cycle tops and below it at the lows, and that fit is what made the model famous. From 2022 on the price has stayed below it, touching it only in March 2024, a month before a halving; since that halving the line has climbed far above the price. The table gives the price as a multiple of the model at each turn. The chart shows the model as history, not as a forecast. A model built from a supply schedule that is known years in advance says nothing about demand.
Questions about the stock-to-flow model
What is the bitcoin stock-to-flow model?
A model that prices bitcoin by its scarcity: the stock of coins in existence divided by the flow of new ones a year. Because the halvings cut the flow in half about every four years, the ratio and the model's price step up at each one.
Why is the stock-to-flow model so far above the price?
Because the model rises with every halving whatever the market does, and from 2022 on the price has not kept up. The table shows the price as a multiple of the model at each cycle turn and at the latest price.
Who created the stock-to-flow model?
The pseudonymous analyst PlanB, in an article published in March 2019. Perly draws a simplified price form of it, 0.4 × SF³, from its own count of the supply, and credits the idea to him under the chart.
Does the stock-to-flow model still work?
From 2012 to 2021 the price moved around it, above it at tops and below it at lows. Since 2022 the price has stayed below it, touching it only in March 2024, and since the halving that April far below it. As a guide to the price it has not held since then.
Why are the dots on the stock-to-flow chart different colours?
Each dot is coloured by the days that were left until the next halving: red just after a halving, purple just before the next. The scale on the right reads the colour in days.
Indicators are descriptive statistics about the past, not predictions. Nothing on this page is financial advice.
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