How issuance approaches 21 million and what the four-year subsidy schedule does—and does not—guarantee. The explanation names what wallets, nodes, and miners each do so their roles do not blur together.
- The halving changes new issuance, not existing coins.
- A known schedule does not dictate a market price.
- Miner revenue gradually shifts toward transaction fees.
The issuance rule
Each valid block may include newly issued bitcoin up to the current subsidy plus transaction fees. The subsidy halves every 210,000 blocks, producing a supply curve that asymptotically approaches 21 million.
What halves
The event cuts the new-coin block subsidy in half. Existing balances are untouched, transaction capacity does not double and the market price is not programmed to rise.
Name the layer and the actor. Wallets create transactions, nodes check rules, miners propose blocks, and Lightning peers manage channels.
Mining after subsidies
As issuance declines, fees are expected to become a larger share of miner revenue. The long transition gives users, miners and the fee market decades to adapt rather than imposing a sudden cutoff.
The schedule, block by block
The subsidy started at 50 BTC per block in January 2009. It halved at block 210,000 in November 2012 to 25, at 420,000 in July 2016 to 12.5, at 630,000 in May 2020 to 6.25, and at 840,000 in April 2024 to 3.125. The next halving at block 1,050,000 is expected in 2028.
The sequence continues until the subsidy rounds to zero satoshis around 2140, by which point about 20,999,999.98 BTC will have been issued. Because issuance is a function of block height, not calendar time, the dates drift with block timing but the amounts never do.
Where the supply is today
Roughly 19.9 million BTC had been issued by 2025, about 95 % of the eventual total, with the remaining 5 % spread over more than a century. Some of the issued coins are gone: outputs untouched since 2010 and known burned addresses suggest millions of BTC are permanently lost, though nobody can measure it directly.
Circulating supply figures on price sites count every issued coin, including lost ones, and differ slightly by method. The supply explorer on this site calculates issuance at any block height from the schedule itself rather than from a third-party estimate.
What a halving does and does not do
A halving cuts the flow of new coins to miners in half overnight, which halves the sell pressure from miners covering costs and, all else equal, raises the difficulty-adjusted cost of producing a coin. It does not change the price by rule; the market does that, and past cycles show gains that began before or long after the event.
It does change miner economics: revenue falls immediately while costs do not, and less efficient operations shut down until difficulty adjusts. Over the long run halvings shift miner income from subsidy to fees, which is the open question about Bitcoin's security budget that the fee market must eventually answer.
Trace the rule through the network
Follow one transaction from wallet signing to node validation, mempool relay, block inclusion, and confirmations. That sequence shows which facts come from consensus and which depend on local policy.
Common questions
When was the last halving?
April 2024, at block 840,000, when the subsidy fell from 6.25 to 3.125 BTC per block. The subsidy is set by block height in the consensus code, so the event is predictable years in advance.
When is the next halving?
At block 1,050,000, expected around early 2028. The date drifts because blocks arrive slightly faster or slower than ten minutes; the block number does not.
How many bitcoin are lost forever?
Nobody can measure it directly. Coins whose keys were lost still count toward the 21 million cap and simply never move; estimates based on long-dormant outputs range into the millions of BTC, and they should be treated as inferences.
Sources and further reading
Primary documents this guide draws on. Links open the original publisher.
- Controlled supply Bitcoin Wiki
- Bitcoin Core: GetBlockSubsidy in validation.cpp Bitcoin Core source
- Bitcoin: A Peer-to-Peer Electronic Cash System Satoshi Nakamoto, 2008