Every 210,000 blocks — approximately every four years — Bitcoin’s block reward is cut in half. This is the halving, and it is hard-coded into the protocol. When Bitcoin launched in January 2009, miners who produced a block received 50 BTC. After the first halving in November 2012, that dropped to 25. Then 12.5 in July 2016, 6.25 in May 2020, and 3.125 after the April 2024 halving. The next halving is scheduled for somewhere around spring 2028, and the reward will drop to 1.5625 BTC per block. The process continues until around the year 2140, at which point the block reward will effectively round down to zero and Bitcoin’s total supply will asymptote toward 21 million coins.
Why the Schedule Exists
Satoshi wanted Bitcoin to have a fixed total supply and a predictable issuance curve. A halving schedule achieves both: every new BTC is minted according to a rule nobody can change, and you can calculate the exact supply at any future block height. This is the thing crypto people point at when they talk about “hard money” — unlike fiat currencies, where the issuing authority can print more whenever it needs to, Bitcoin’s supply schedule is set in code that would require a hard fork to change, and a hard fork that increased supply would almost certainly not get adoption from miners, nodes, or holders.
The four-year interval is not magic. It is just what you get when you space 210,000 blocks at a 10-minute average block time. The fact that it lines up roughly with US presidential election cycles is a coincidence, though it has become part of the mythology.
The Cycle Narrative
Bitcoin’s price history is often described in terms of halving cycles. The claim is that each halving cuts new supply in half while demand stays roughly constant, so the price has to rise to clear the market. Looking at the data from the 2012, 2016, and 2020 halvings, prices did in fact run hard in the 12 to 18 months after each one — the 2013, 2017, and 2021 bull runs are all adjacent to a halving. Whether that is cause and effect, or whether it is just that retail attention increases around the halving and drives a speculative mania, is genuinely debatable. The 2024 halving was followed by a run that peaked around $108,000 in late 2024, broadly continuing the pattern, though by that point so many people expected the pattern that it had partially priced itself in.
The counter-argument is that halvings are fully known in advance — the schedule is public and has been since 2009 — so an efficient market should have already priced them in and there should be no reason to expect a jump at each one. The efficient market argument is harder to make about Bitcoin than about most assets, though, because the buyer base is heavily retail and retail attention is notoriously not efficient.
What It Means for Miners
For miners, the halving is an income cut. The day before the 2024 halving, miners were earning 6.25 BTC per block plus transaction fees. The day after, they were earning 3.125 BTC plus fees. The hashrate briefly dipped as the least efficient miners shut down, then recovered as the rest of the network absorbed the slack. Each halving acts as a forced upgrade cycle: anyone running old, power-hungry ASICs becomes unprofitable overnight and either replaces their hardware or exits the business. This is one of the reasons why Bitcoin’s energy efficiency improves over time despite rising hashrate.