Strip away every price chart and Bitcoin is a specific, fully public set of rules, first published by Satoshi Nakamoto in Bitcoin: A Peer-to-Peer Electronic Cash System (31 October 2008). Transactions are recorded against unspent transaction outputs (UTXOs) rather than account balances; a new block of transactions is proposed roughly every ten minutes by whichever miner first solves a proof-of-work puzzle (finding a number that makes the block's hash fall below a target), a difficulty that self-adjusts every 2,016 blocks to hold the ten-minute average steady regardless of how much computing power joins the network; and the miner who wins that block is paid a block reward in newly created bitcoin, which halves every 210,000 blocks (roughly every four years) and caps total issuance at 21 million BTC.
What is Bitcoin's halving schedule?
That schedule is not a promise, it is arithmetic you can run yourself, and doing so is the point of this section. Simulating the halving schedule in integer satoshis (1 BTC = 100,000,000 satoshis, reward floor-divided by two at each 210,000-block boundary) gives a maximum eventual supply of 20,999,999.9769 BTC, a hair under the commonly quoted "21 million," because integer rounding at each halving loses a few hundred satoshis' worth of reward along the way. Block reward started at 50 BTC (2009) and has halved on schedule: 25 BTC (28 Nov 2012), 12.5 BTC (9 Jul 2016), 6.25 BTC (11 May 2020), and 3.125 BTC (the fourth halving, at block 840,000, 19–20 Apr 2024). Summing the first four eras (210,000 blocks each at 50, 25, 12.5, and 6.25 BTC) gives 19,687,500 BTC mined through the fourth halving: 93.75% of the eventual 21-million cap already issued the moment that halving occurred. The next halving (block ~1,050,000, roughly 2028) drops the reward again to 1.5625 BTC.
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What is stock-to-flow, and does it predict the price?
One derived metric worth knowing because it is genuinely computable, and worth being skeptical of because of what has been built on top of it: stock-to-flow, the ratio of the existing stock to the annual new flow. At 6 blocks/hour × 24 × 365 = 52,560 blocks/year, the post-2024-halving annual flow is 52,560 × 3.125 ≈ 164,250 BTC/year, against a stock of 19,687,500 BTC at that halving point, a stock-to-flow ratio of ≈120. That number is a real, protocol-derived fact about scarcity, comparable in spirit to gold's own stock-to-flow ratio (commonly cited in the 60s). What is not a real, protocol-derived fact is the claim, popularized under the "PlanB" stock-to-flow model, that this ratio predicts Bitcoin's price on a specific mathematical curve, that model made public, falsifiable price forecasts that the market subsequently traded well below, and its failure is itself a useful, citable case study in exactly the pattern this module exists to catch: a real, computable, sourced mechanical fact (stock-to-flow is ≈120) laundered into an unrelated, unfalsifiable-until-it-fails investment claim (stock-to-flow therefore implies a price). Learn to hold the two apart every time you meet this pattern in this asset class, because you will meet it constantly.