How many bitcoin will ever exist?

No company or central bank decides how many bitcoin there are. The number is set by a schedule in bitcoin’s software: new coins are created only as a reward for adding a block to the chain, and the reward halves at fixed points until it reaches zero. Every node, a computer running that software, checks every block against the schedule.

The schedule adds up to just under 21 million. It was broken once, in August 2010, until the next day. And millions of the coins it has created are believed lost for good.

Where the 21 million comes from

Satoshi Nakamoto, who created bitcoin, set the number out in January 2009, when the first version of the software came out: “Total circulation will be 21,000,000 coins,” handed to whoever makes blocks, “with the amount cut in half every 4 years.”

In the code, the first transaction of each block may pay the miner who made it a fixed amount of new bitcoin, the block subsidy, plus the fees of the transactions in the block. The subsidy started at 50 bitcoin, and every 210,000 blocks it’s cut in half: the halving. About every two weeks, the network adjusts how hard it is to make a block, so that one comes every 10 minutes on average, and 210,000 blocks take about four years. A comment in the code of Bitcoin Core, the program that grew out of Satoshi Nakamoto’s first version, says so: the subsidy “is cut in half every 210,000 blocks which will occur approximately every 4 years.”

The first 210,000 blocks created 10.5 million bitcoin, half the total. Each period after that creates half as many as the one before: 5.25 million, then 2.625 million, and so on. Halved again and again, the total creeps toward 21 million and never reaches it.

Why it stops just short of 21 million

Bitcoin’s software counts every amount in whole satoshis, hundred-millionths of a bitcoin. The subsidy started at 5 billion satoshis. When halving it would leave a fraction of a satoshi, the code drops the fraction, and after the 33rd halving, at block 6,930,000, the subsidy rounds down to zero. Added up, the schedule comes to 20,999,999.9769 bitcoin.

Some of that will never exist, and some will never move. A miner may claim less than the subsidy, and what it leaves unclaimed is never created: in December 2017, the miner of block 501,726 claimed nothing at all, and the 12.5 bitcoin that block could have created never came into being. The 50 bitcoin of the first block, in January 2009, can’t be spent, because of a quirk in how the code treats that block. In all, about 230 bitcoin can never be spent, those 50 among them, according to The Block in March 2026.

Bitcoin Core’s code says as much. There, 21 million is a check that no single amount is larger, not the supply: a note next to it says the supply “currently happens to be less than 21,000,000 BTC for various reasons.”

The halvings so far

Each halving happens at a block number, not on a date, and so far each has come before four years were up: blocks have arrived, on average, slightly faster than every 10 minutes.

	Block	When	New bitcoin per block	Created by the end of the period
Start	0	January 2009	50	10,500,000
First halving	210,000	November 2012	25	15,750,000
Second	420,000	July 2016	12.5	18,375,000
Third	630,000	May 2020	6.25	19,687,500
Fourth	840,000	April 2024	3.125	20,343,750
Fifth	1,050,000	Expected around April 2028	1.5625	20,671,875
33rd, the last	6,930,000	Expected around 2140	0	20,999,999.9769

At about 144 blocks a day, the fourth halving cut the new supply from about 900 bitcoin a day to about 450. The fifth will cut it to about 225.

How many there are now

In March 2026, block 939,999 brought the total created to 20 million, a little over 17 years after the first block, according to The Block. On October 29, 2026, the chain reached block 973,714, according to mempool.space. By the schedule, that’s about 20.1 million bitcoin created, 95.7% of all there will ever be.

Fewer than 895,000 are left, and they’ll take more than a century: about 238,000 before the next halving, in 2028, and about 656,000 over the 112 years after it. Anyone can repeat the count: take the latest block number from a block explorer and apply the table above.

What happens after the last one

At about one block every 10 minutes, block 6,930,000 is due around 2140. From then on, miners will be paid only by the network fees of the transactions they include. For now, fees are a small part of what they earn: over the year to October 2026, less than 1% of what a block paid its miner, according to mempool.space’s data. The rest was new bitcoin.

The whitepaper that introduced bitcoin, in October 2008, expected that “the incentive can transition entirely to transaction fees,” and the FAQ on bitcoin.org says miners “will probably be supported exclusively by numerous small transaction fees.” Whether fees alone will pay enough to keep miners securing the network is a question for the coming decades.

The day someone created 184 billion bitcoin

The limit is only as good as the software that enforces it, and that software has failed.

In August 2010, a transaction in block 74,638 created about 184 billion bitcoin, almost 9,000 times the whole schedule. The code that checked transactions didn’t handle outputs so large that their sum overflowed, and someone used that to create two outputs of about 92 billion bitcoin each. The flaw, catalogued as CVE-2010-5139, let an attacker “bypass intended economic restrictions and create many bitcoins.”

A user of the Bitcointalk forum posted that the block’s “value out” was “quite strange.” Satoshi Nakamoto asked people to stop mining (“It would help if people stop generating”) and, within about five hours of the discovery, released a corrected version. It rejected the transaction, and any output over 21 million bitcoin. Nodes running it ignored block 74,638 and every block built on it, miners built a new chain without it, and the next day, at block 74,691, that chain overtook the bad one. The 184 billion bitcoin don’t exist on the chain the network follows today.

A second bug of the kind turned up in September 2018. An anonymous reporter sent Bitcoin Core’s developers what looked like a bug that could crash nodes; within hours, they found it could also let a miner create bitcoin out of nothing, by spending the same coins twice. Fixed versions were out the next day, and the developers said they were unaware of any attempt to exploit it.

Both were fixed the same way: people chose to run new software. That is also what makes the limit hard to change.

Why the limit is hard to change

Every node checks every block it receives. In Bitcoin Core, a block that pays its miner more than the subsidy plus the fees in it is rejected as invalid. As the FAQ on bitcoin.org puts it: “Every Bitcoin node in the world will reject anything that does not comply with the rules it expects the system to follow.”

So no developer, miner or company can raise the limit by announcing it. Developers “can’t force a change in the Bitcoin protocol,” the FAQ says, “because all users are free to choose what software and version they use.” A miner that paid itself more would produce blocks every other node throws away.

Raising the limit would take the people who run nodes, exchanges among them, switching to software with a different rule. Nothing stops anyone from writing that software or running it. But nodes that kept the old rule would reject the new coins, and the network would split in two, each side with its own rules. The 21 million holds for as long as the people who run bitcoin keep choosing software that enforces it.

Not every bitcoin can move

When the private key to some bitcoin is lost, the coins stay where they are: in the count, and out of everyone’s reach. The schedule doesn’t replace them, and no one can reissue them.

How many there are is an estimate, since a lost coin looks just like one whose owner is waiting. In March 2020, Chainalysis estimated that 3.75 million bitcoin were lost, about a fifth of the 18.27 million created by then, and counted the other 14.52 million as available. The guide on custody has some of the stories behind a number like that, and the one on inheritance explains what happens when an owner dies without passing on the key.

And a coin that hasn’t moved in years isn’t necessarily lost. In July 2025, more than 80,000 bitcoin that had sat untouched since April 2011 moved and were sent to Galaxy Digital, according to The Block; later that month, Galaxy said it had sold more than 80,000 bitcoin for a “Satoshi-era investor.”

So the supply that can move is smaller than the count, by an amount no one knows exactly.

The limit counts coins, not promises

The schedule limits the coins on the network. It doesn’t limit the balances on a company’s books, which are promises, and a company can owe more bitcoin than it has. When the exchange Mt. Gox filed for bankruptcy in February 2014, NPR reported that it might have lost 750,000 of its customers’ bitcoin, essentially all of them, and about 100,000 of its own. For those customers, the 21 million made no difference: what they held was the exchange’s promise. The guide on custody tells what came back, and when.

What to do

• Read 21 million as a rule you can check, not as a promise. The schedule is public, every node enforces it, and the latest block number is all it takes to work out how many bitcoin have been created.
• Owning bitcoin doesn’t mean owning a whole one. Amounts go down to a satoshi, the unit bitcoin’s software counts in.
• Count coins, not balances. The 21 million covers coins on the network. A balance at an exchange is a claim on a company, worth what the company can pay.
• Guard your keys. A lost coin stays in the count and out of reach for good, and nothing will replace it. For savings, use a setup that passes the test in the guide on hardware wallets, multisig and collaborative custody.