Bitcoin Stock-to-Flow Model
Understanding Bitcoin's scarcity and its relationship to value over time
What is Stock-to-Flow?
Stock-to-Flow (S2F) is a model that measures the scarcity of an asset by comparing the existing supply (stock) to the new production (flow).
Higher S2F ratio = More scarce = Harder money
Bitcoin's S2F ratio increases approximately every 4 years during "halving" events, when the block reward (new Bitcoin production) is cut in half. This makes Bitcoin progressively scarcer over time.
Stock
The total existing supply of an asset. For Bitcoin, this is all BTC that have been mined so far (currently ~19.7 million BTC).
Flow
The new production added annually. For Bitcoin, this is the amount of new BTC mined each year through block rewards.
S2F Ratio
Stock divided by Flow. Shows how many years of current production would be needed to match the existing stock. Higher = More scarce.
The Formula
For Bitcoin: S2F = Total Mined BTC / BTC Mined Per Year
⚙️ Interactive S2F Calculator
Comparing to Other Assets
| Asset | Stock (Total Supply) | Flow (Annual Production) | S2F Ratio | Hardness |
|---|---|---|---|---|
| Gold | ~208,000 tonnes | ~3,500 tonnes/year | ~59 | Hard Money (historically) |
| 🥈 Silver | ~1,740,000 tonnes | ~25,000 tonnes/year | ~22 | Moderate |
| ₿ Bitcoin (2024) | ~19.7 million BTC | ~164,000 BTC/year | ~120 | Hardest Money Ever |
| ₿ Bitcoin (2140) | 21 million BTC | 0 BTC/year | ∞ | Perfectly Scarce |
| Fiat Currency | Variable | Unlimited (can be printed) | < 1 | Soft Money |
Bitcoin Halving Timeline
Block Reward: 50 BTC
S2F: ~1.5 (Similar to copper)
Bitcoin's genesis. High inflation, low scarcity.
Block Reward: 25 BTC (1st Halving)
S2F: ~8 (Similar to collectibles)
First halving event. Price rallied from $12 to $1,000.
Block Reward: 12.5 BTC (2nd Halving)
S2F: ~22 (Similar to silver)
Bitcoin reaches silver-level scarcity. Price: $650 → $20,000.
Block Reward: 6.25 BTC (3rd Halving)
S2F: ~56 (Approaching gold)
Near gold-level scarcity. Price: $9,000 → $69,000.
Block Reward: 3.125 BTC (4th Halving)
S2F: ~120 (Surpasses gold)
Bitcoin becomes scarcer than gold. Current era.
Block Reward: Continues halving every 4 years
S2F: Approaches infinity
By 2140, all 21 million BTC will be mined. No more inflation.
Key Takeaways
- Bitcoin's S2F increases over time due to programmed halvings every 4 years
- Higher S2F = More scarce = Harder money that's resistant to inflation
- Bitcoin already surpasses gold in scarcity (S2F ~120 vs Gold's ~59)
- By 2140, Bitcoin will have infinite S2F when the last BTC is mined
- The model suggests that as S2F increases, so does Bitcoin's market value
- No other asset has a predictable, programmatic scarcity schedule like Bitcoin
⚠️ Important Notes
The S2F model is not a price prediction tool. While historical data shows correlation between S2F and price, past performance doesn't guarantee future results. Many factors affect Bitcoin's price beyond scarcity alone.
S2F is best used as a framework for understanding Bitcoin's monetary properties and programmatic scarcity, not as investment advice.