Halving history and the issuance schedule

Bitcoin has no central issuer. New coins enter circulation only as the reward a miner collects for assembling a valid block, and that reward is written into the protocol rather than set by any committee. Satoshi Nakamoto fixed the initial reward at fifty bitcoin per block and added a rule that it would be halved every 210,000 blocks — roughly four years at the ten-minute target. The rule is enforced by every node independently: a block that claims more than the current subsidy is rejected outright, no matter how much work went into finding it.

The arithmetic behind the twenty-one million cap is a geometric series. Fifty bitcoin per block for 210,000 blocks yields 10.5 million coins. The next epoch yields half that, the one after half again, and so on. The sum of 10.5 million multiplied by the series 1 + ½ + ¼ + … converges on 21 million. The cap is not a target the network aims at; it is the limit the halving rule approaches and never quite reaches. Because the subsidy is denominated in whole satoshis and eventually rounds to zero, the final coins will be mined in the middle of the next century, and the last satoshi will never be issued at all.

The schedule matters for two reasons. The first is scarcity: the flow of new supply is known decades in advance and cannot be increased by any participant, which is a property no central bank can offer. The second is miner economics. Miners earn the subsidy plus transaction fees, and the subsidy is the larger share of that revenue today. Each halving cuts the largest line of miner income in half overnight, which forces the least efficient operators out and pushes the rest toward cheaper power. That pressure is a feature of the design, not a flaw: it is how a fixed-supply network disciplines its own cost base.

The chart below shows both quantities at once. The bars are the subsidy in bitcoin per block for each epoch; the line is the annual issuance that subsidy produces across a year of blocks. The two fall together, and the shape is the point — issuance is not declining gradually, it is stepping down by half at fixed intervals.

The halving's most influential framing has been stock-to-flow. The ratio compares the existing stock of an asset — everything already above ground — with the flow of new production in a year. Gold carries a ratio near sixty; silver near twenty; a fiat currency under a loose monetary policy can sit near one. Bitcoin's ratio rises with every halving, and by the mid-2020s it had passed gold's. The argument built on top of that number was that scarcity and price move together, so a rising ratio implied a rising price, and the model was fitted to bitcoin's history and extrapolated forward.

The criticism is not that scarcity is irrelevant. It is that the model treats a single supply variable as sufficient to explain a price that is set by demand as well, and demand is not in the equation. A ratio can rise while price falls if the marginal buyer steps away, and that is exactly what happened in 2022. The model was also fitted after the fact to a short series with only three halvings in it, which leaves very little evidence to distinguish a real relationship from a coincidence. When its most confident projections failed to materialise, the honest reading was not that the halving stopped mattering but that a supply ratio is not a price model.

What survives the criticism is narrower and more useful. The halving reliably reduces the flow of new supply, and that reduction is knowable in advance. Whether the market has already priced it, and how demand responds, are separate questions that the schedule cannot answer. Readers who want to see how a fixed issuance schedule compounds into a supply curve can work through the arithmetic themselves rather than take a model's word for it.

The first halving, in November 2012, cut the reward from fifty bitcoin to twenty-five. Bitcoin was four years old, thinly traded, and worth roughly twelve dollars. The event passed with little market drama; the more consequential change was that the network had now demonstrated the rule would execute on schedule without anyone deciding to execute it.

The second, in July 2016, took the reward to 12.5 bitcoin with the price near $650. By then the halving had become an anticipated event, and the months around it were marked by speculation about whether the market would front-run the supply cut. The third, in May 2020, arrived in the middle of a global pandemic and cut the reward to 6.25 bitcoin at a price near $8,600. The fourth, in April 2024, took it to 3.125 bitcoin with the price near $64,000 and spot exchange-traded funds already trading in the United States — a demand channel that did not exist at any earlier halving.

Read together, the four events show a schedule that has never missed and a market that has changed around it. The supply rule is constant; the participants, the instruments and the price level are not. That is the tension worth holding on to when the next halving is discussed as though its outcome were already known.