Bitcoin is valuable due to its growing adoption and scarcity by design – new bitcoins are minted through a process called mining, and the maximum supply is fixed at 21 million bitcoins. With that being said, how much Bitcoin is left to mine? The answer: less than 1.3 million. The vast majority of bitcoins are already mined and in circulation. However, the process of mining goes on forever, and the balance of the Bitcoin supply won’t be fully mined until 2140.
In this guide, we’ll examine the Bitcoin mining process to learn how much Bitcoin is left to mine, how the supply is governed, and how Bitcoin halvings, mining difficulty, and lost Bitcoin play into the big picture. Let’s start with Bitcoin mining to understand the process of bringing new bitcoins into circulation.
Overview of Bitcoin Mining
Bitcoin mining refers to the process of validating network transactions and minting new bitcoins. Because mining also validates network transactions, mining will continue long after the last bitcoin is mined.
The Bitcoin blockchain stores transactions in batches called blocks. If Alice sends one bitcoin to Bob, this transaction, along with thousands of others, is recorded in a block. Each block links to the prior block using a hash value of data from the prior block.
Hashes refer to a method of encryption that turns data into an alphanumeric string. They are used throughout the Bitcoin protocol, which uses SHA-256 encryption to generate hashes.
- Input Data: Alice sent Bob one Bitcoin.
- SHA-256 Hash Output: b5c3e620f7244f4e3687fb1fa3b80af17a71ea91ca0733a953a017716a4a6afc
Bitcoin’s mining process, called proof of work (PoW), also uses these hash values. Transactions are hashed and then paired, and then hashed again until one hash represents all the transactions in a proposed block. This final hash value of block transactions is called the Merkle root. Miners check for double-spending as part of the validation process as well.
Mining itself is based on hashing, using the Merkle root, the prior block’s hash, and a nonce (number used only once) to find a qualifying hash based on the network difficulty level. In short, Bitcoin mining consists of high-speed guessing, using the SHA-256 algorithm to generate hashes.
The miner who finds a qualifying hash first gets to add a new block of transactions to the Bitcoin blockchain. Currently, miners earn 3.125 bitcoins for mining a block, plus any fees paid for transactions within the block. The fees ensure Bitcoin miners still have an incentive to validate transactions long after the last bitcoin has been mined.
Total Supply of Bitcoin
The Bitcoin protocol caps the maximum supply of Bitcoin at 21 million bitcoins. While this cap is written in software that can be changed, miners share a powerful incentive to maintain the cap at 21 million bitcoins.
In effect, the cap is enforced by node operators who choose which version of Bitcoin Core software to run. If there were a new version of the software that boosted the supply to 210 million bitcoins, for example, miners would continue using the old version that capped the supply at 21 million. Boosting the maximum supply works against their financial best interests by reducing the value of each bitcoin.
However, because Bitcoin is divisible, the capped supply isn’t an issue. There’s plenty of Bitcoin for everyone, although relatively few people own Bitcoin in comparison to dollars or other traditional assets.
Bitcoin’s digital scarcity, enforced by a decentralized, worldwide network of node operators, makes it valuable. By contrast, traditional currencies increase in supply. Bitcoin’s maximum supply remains fixed, and the emission rate slows over time due to the Bitcoin halving, which occurs every four years on average.
The chart below illustrates the price of one bitcoin relative to the global money supply (M2). What began as a loose correlation between the two in 2014 has become much closer, suggesting more people see Bitcoin as a hedge against inflation as the money supply grows.
Data from the Federal Reserve shows that the US money supply has grown steadily since 1960, with a steep ascent in 2020.
Traditional fiat currencies grow in supply, creating more units of currency competing for goods and services. The resulting price inflation acts as a silent tax on savers and consumers. Bitcoin, however, is finite, making it sound money that can increase in value and purchasing power.
How Much Bitcoin Has Been Mined So Far?
As of this writing, 19,771,043 bitcoins exist. Tools like CoinMarketCap provide updated data on the circulating supply of Bitcoin. However, while that makes it easy to calculate how much Bitcoin is left to mine, it doesn’t reflect the true usable supply of Bitcoin. Let’s dig into the numbers to see how they fit together.
1. How Many Bitcoins Are Lost?
Estimates on the amount of Bitcoin lost forever range from three million to more than six million, or somewhere between 14% and 30% of the total supply once all the Bitcoin has been mined. How does a bitcoin become lost? It’s easier than you might think.
Bitcoin uses digital wallets to store Bitcoin balances. However, there’s really no Bitcoin in these wallets. Instead, the wallets hold private keys that control Bitcoin assets on the blockchain. Without access to the wallet’s private keys, nobody can access the Bitcoin balance secured by the wallet. The wallet’s Bitcoin sits in a sort of blockchain purgatory forever.
Bitcoin wallets use a seed phrase, which is a human-readable version of the wallet’s private key, usually comprised of 12, 18, or 24 words. Without this seed phrase or the private key, the wallet can’t sign transactions, meaning all access to the wallet’s assets is lost.
Losing the wallet seed phrase frequently results in losing access to valuable Bitcoin. Imagine how easy it might be to lose a slip of paper with a dozen words scribbled on it—or not be able to read the words. It happens frequently. A New Yorker article tells the tale of one man who inadvertently discarded the hard drive that held the keys to his Bitcoin, valued at a half-billion dollars. At the high end of estimates, more than $400 billion worth of Bitcoin may be lost forever, making the remaining Bitcoin more valuable.
2. Current Mined Supply
Early Bitcoin mining paid a mining reward of 50 bitcoins, swelling the supply quickly. However, Bitcoin also uses a halving schedule to reduce the mining reward, also called a block subsidy, by half every 210,000 blocks. You can see the effect on the chart as it begins to flatten more with each halving event. Once all the bitcoins have been mined, the trailing end of the chart will be flat.
Let’s look at some dates and stats through Bitcoin’s history to track the slowing growth in supply.
At launch, the Bitcoin protocol rewarded successful miners with 50 bitcoins. This reward has been cut in half four times since then.
- Nov. 28, 2012: 25 bitcoins. By the first Bitcoin halving, about 10 million bitcoins were mined.
- July 9, 2016: 12.5 bitcoins. The second halving saw the total supply increase to about 15 million.
- May 11, 2020: 6.25 bitcoins. Supply at Bitcoin’s third halving had increased to 18 million bitcoins.
- April 19, 2024: 3.125 bitcoins: By the fourth halving, Bitcoin supply had reached 19.7 million.
Halvings reduce the emission rate by 50% about every four years, with the last bitcoin expected to be mined in 2140. To date, 19.77 bitcoins have been mined, and supply growth will continue to dwindle (due to halvings) until all bitcoins have been mined.
3. Halving Events and Their Impact
Bitcoin’s halving events help promote a sustainable economy by adding larger amounts of supply in the protocol’s earlier days and decreasing supply growth as Bitcoin matures. As described earlier, Bitcoin miners compete to solve an algorithmic puzzle. The first miner to find a qualifying hash earns the mining reward for that block. Currently, the mining reward is 3.125 bitcoins, and this amount will be cut by 50% when the next 210,000 block milestone is reached.
Halving events reduce supply growth, but they also reduce rewards for mining. You might think that would decrease interest in mining, an essential component that secures the blockchain. However, that hasn’t been the case. The global hash rate has steadily increased, despite periodic halvings, as shown below, reaching more than 780 terahashes per second by late 2024.
Each hash is a guess in the attempt to mine a new block. These guesses aren’t random, however. Instead, they follow a formula that requires quadrillions of hash calculations to solve a block. This is the work in “proof of work” for Bitcoin.
Rather than seeing reduced interest in mining, Bitcoin’s global hash rate has increased exponentially since its launch despite periodically halving mining rewards. Three other key factors play into this.
- BTC Price: Bitcoin’s continued price rise helps keep Bitcoin mining profitable.
- Transaction Fees: Fees from Bitcoin transactions bring additional income for miners.
- Mining Efficiency: Bitcoin mining tech continues to evolve, with specialized equipment like application-specific integrated circuits (ASICs) improving mining efficiency.
While the supply growth will continue to shrink and rewards due to reduced mining subsidies, mining interest remains high and could continue growing alongside Bitcoin’s price.
How Much Bitcoin is Left to Mine?
As of this writing, 1,228,957 bitcoins are still unmined. On average, this amount decreases every ten minutes, with the current block subsidy fixed at 3.125 bitcoins per block for the next few years.
Although 19.77 million bitcoins have already been mined out of a total of 21 million, the remaining unmined bitcoins will take more than a century to mine fully. Supply growth will continue to flatten, with halvings occurring every 210,000 blocks, or about four years. Fees paid as part of block rewards come from users, so they don’t affect supply.
Mining Difficulty and Timeframe
The Bitcoin protocol uses periodic difficulty adjustments to keep the average block time close to 10 minutes. Halving events have no effect on the time required to mine a new block. Instead, mining frequency is governed by adjusting the difficulty. Every 2,016 blocks (approximately two weeks), the Bitcoin protocol adjusts the difficulty of mining a block based on the hash rate. As hash rates increase, difficulty also increases. Similarly, difficulty drops when hash rates decrease.
While Bitcoin’s price doesn’t affect the difficulty level, a general directional trend connects the two.
Because difficulty adjustments work in both directions, they have no meaningful impact on when the last bitcoin will be mined. Difficulty also has no effect on how much Bitcoin is left to mine because the 21-million maximum supply is governed by Bitcoin Core software, with the global community enforcing the limit.
Bitcoin mining subsidies (minting new bitcoins) will continue for nearly 120 more years until the last bitcoin is mined around 2140.
The Future of Bitcoin Mining
Future Bitcoin halving events will slow mining subsidies. Let’s look at the math for block subsidy at launch versus the first several halvings.
- Launch: 50 bitcoins
- 1st Halving (Nov. 28, 2012): 25 bitcoins
- 2nd Halving (July 9, 2016): 12.5 bitcoins
- 3rd Halving (May 11, 2020): 6.25 bitcoins
- 4th Halving (April 19, 2024): 3.125 bitcoins (current)
- 5th Halving: 1.5625 bitcoins (mid-2028 expected)
- 6th Halving: 0.78125 bitcoins
- 7th Halving: 0.390625 bitcoins
- 8th Halving: 0.1953125 bitcoins
- 9th Halving: 0.09765625 bitcoins
Within the next 20 years, Bitcoin mining subsidies will fall below a 1/100th of a bitcoin per block. However, if Bitcoin adoption continues and the price of Bitcoin continues to rise, mining is expected to remain popular because miners also earn transaction fees.
If mining interest wanes and the hash rate falls, the difficulty will adjust, making mining more attractive again. This clever structure helps ensure an active mining community secures the blockchain even as block subsidies wind down and eventually end.
What Happens When All Bitcoins Are Mined?
By design, Bitcoin mining provides two types of earnings. The first is block subsidies, which represent the newly minted bitcoins and are expected to end by 2140. The second part of earnings comes from network fees. When Alice sends Bob one Bitcoin, Alice pays a fee for using the Bitcoin network. These fees are expected to exceed block subsidies as Bitcoin adoption grows. They’re also expected to increase in value as Bitcoin’s value increases.
In short, the Bitcoin network should remain sustainable even after all the bitcoins have been mined. The Bitcoin protocol provides features to ensure this sustainability, including the ability to reduce mining difficulty if the price of Bitcoin or decreased rewards make mining less attractive. Downward difficulty adjustments can reduce the cost of mining, encouraging miners sitting on the sidelines to begin mining again.
Environmental and Energy Concerns Around Bitcoin Mining
One common criticism of Bitcoin centers on energy consumption. According to one 2023 estimate, Bitcoin mining accounts for between 0.2% and 0.9% of global electricity consumption, putting it on par with nations like Greece. However, these estimates should be viewed in context. Many Bitcoin miners have moved toward using renewable energy and “trapped energy,” which we’ll discuss shortly.
Still, the energy demands of proof-of-work can be considerable, which led many protocols to switch to proof of stake (PoS), using collateral to validate transactions and secure the blockchain. For example, Ethereum switched to PoS in 2022.
The Shift to Renewable Energy
On the other side of the Bitcoin energy debate, some sources estimate that more than half of Bitcoin’s energy requirements come from sustainable sources. The trend in sustainable energy for Bitcoin mining continues up and to the right, giving more context to some of the more alarming numbers often cited.
Bitcoin miners have also turned to “stranded energy” and excess energy that would otherwise go unused. This trend toward eco-friendly energy sources is expected to continue, minimizing Bitcoin’s environmental impact.
Conclusion
Although just over 1.2 million bitcoins remain to be mined, that number is only part of the story. The rest of the journey will take until about 2140, when the last bitcoin is expected to be mined. However, bitcoin mining can continue indefinitely. Miners also earn fees for transactions within the blocks they mine, so mining can continue indefinitely. Periodic automated adjustments to Bitcoin’s mining difficulty help ensure that mining costs remain aligned with income opportunities for miners.
FAQs
What will happen when 100% of Bitcoin is mined?
Who owns the most Bitcoin?
How long does it take to mine 1 bitcoin?
Will Bitcoin reach 1 billion?
How many bitcoins are left to mine in 2024?
References
- M2 (M2SL) (stlouisfed.org)
- Bitcoin (CoinMarketCap)
- Half a Billion in Bitcoin, Lost in the Dump (newyorker.com)
- Bitcoin Network Hash Rate (I:BNHR) (ycharts.com)
- Tracking electricity consumption from U.S. cryptocurrency mining operations (eia.gov)
- Proof-of-stake (PoS) (ethereum.org)
- Bitcoin mining sustainable energy usage hits all-time high of 54.5% (cointelegraph.com)
- Bitcoin Scoops Up Stranded and Excess Power (aier.org)