--- title: "What does it mean that Bitcoin is limited? The 21-million cap, explained" description: "Bitcoin issues new units on a fixed schedule written into the code since 2009. Today 95.7% of a 21-million cap already exists. What the cap means and how it is used." canonical: https://www.efyfinance.com/en/help-center/blog/emision-bitcoin/ lang: en --- [About us](https://www.efyfinance.com/en/about-us) [Products](https://www.efyfinance.com/en/products) [Multi-currency accounts Operate in USD, EUR, BRL and more](https://www.efyfinance.com/en/products/cuentas-multimoneda) [Digital wallet Balance, transfers and collections](https://www.efyfinance.com/en/products/wallet-digital) [efy Card Global corporate card](https://www.efyfinance.com/en/products/efy-card) [Currencies](https://www.efyfinance.com/en/currencies) [For business](https://www.efyfinance.com/en/for-business) Company [Infrastructure](https://www.efyfinance.com/en/infrastructure) [Success stories](https://www.efyfinance.com/en/success-stories) [Contact](https://www.efyfinance.com/en/contact) Help center Content [**Blog and articles** Guides and concepts](https://www.efyfinance.com/en/help-center/blog) [**Product news** Launches and improvements](https://www.efyfinance.com/en/help-center/news) Help center [**Frequently asked questions** Quick answers](https://www.efyfinance.com/en/help-center/faq) [**Tutorials and how-tos** Step by step](https://www.efyfinance.com/en/help-center/tutorials) [**Support** WhatsApp, call, and social](https://www.efyfinance.com/en/help-center#soporte) [Browse the whole information center](https://www.efyfinance.com/en/help-center) Account Choose how to continue **Personal** Personal account **Business** Business account [Help center](https://www.efyfinance.com/en/help-center) › [Blog](https://www.efyfinance.com/en/help-center/blog) › Concepts Concepts # What does it mean that Bitcoin is limited? ![David Angarita](https://www.efyfinance.com/assets/authors/david-angarita.jpg) [David Angarita](https://www.efyfinance.com/en/about-us) Head of Operations & FX Trader September 24, 2026 · 6 min read Share When someone asks what Bitcoin is, the conversation almost always drifts toward the price. It is the noisiest part and probably the least useful for understanding what it actually is. The technical answer is much shorter: Bitcoin is a public network of computers that keeps a shared record of transactions and issues new units on a fixed schedule, written into the software since 2009. That schedule is what is worth looking at. It says how many units exist today, how many will exist in total and when. No committee decides it and it is not revised every quarter: it is in the code, and anyone can check it by running a node or looking at a public explorer from a browser. Hence the idea I want to put forward, calmly: the most interesting thing about Bitcoin is not its price, but that it is probably the first asset whose monetary policy can be verified instead of believed. Whether that is valuable or not is a legitimate, open debate. Whether it is verifiable is not: it takes ten minutes to check and depends on no one’s opinion. ## The cap, and the schedule that leads to it The maximum is 21 million units. You get there by a simple rule: the network hands a reward to whoever processes each block of transactions, and that reward is cut in half every 210,000 blocks, roughly every four years. This is what is known as halving. Bitcoin issuance schedule ## 95.7% of all the bitcoin that will ever exist already exists Each bar is the total issued by the end of a period. **Every four years** the block reward is cut in half (halving): the bars approach the 21-million cap but never cross it. Source: Bitcoin protocol rules. Totals at the end of each halving period; 2028 is estimated. Hover over a bar or move through them with the keyboard. In present terms: as of this writing the network is at block 968,300 and about 20.09 million units have been issued, that is, around 95.7% of the total that will ever exist. Current issuance is 3.125 units per block, about 450 a day, about 164,250 a year. Against the circulating supply, that comes to 0.82% a year, and the percentage will keep falling in each period. All of these numbers come from two public data points, the block height and the current reward, and are reproduced with a multiplication. ## “Deflationary” is not quite the word Here a distinction that often gets lost is worth making, and in my view it is the most educational part of the topic. A deflationary asset is one whose supply contracts. Bitcoin’s does not contract: it still grows, at that 0.82% a year, only less and less until it stops. The more precise term is “disinflationary with a hard cap”. The distinction is not a vocabulary quibble. An asset with decreasing issuance and a known ceiling behaves differently from one whose supply is actively reduced, and confusing the two leads to expectations the design never promised. There is, however, a genuinely deflationary component, but it comes another way: units whose keys are lost leave circulation permanently, because there is no mechanism to recover them. Exactly how many, no one knows. Widely differing estimates circulate, and the honest thing is to treat them as estimates and not as data. ## What it is used for today, in practice Beyond the debate over whether it is worth holding, there are uses that are already working and that can be described without getting into whether the asset will go up or down. The clearest is its use as collateral. On September 21, 2026 Circle enabled a service for institutional Circle Mint clients to borrow USDC by putting up bitcoin as collateral, without selling the bitcoin. The mechanism is instructive: the bitcoin is held in custody by Circle National Trust and represented as cirBTC, a one-to-one backed token, which serves as collateral in third-party lending protocols (Morpho is the first compatible one) on the Arc or Ethereum networks. Positions are overcollateralized, and the rates, collateral requirements and liquidation thresholds are set by that lending market, not by Circle. The service excludes New York clients. That design solves a concrete and very old treasury problem: I need liquidity, I have an asset, and selling it has tax, accounting or positioning consequences I would rather avoid. It is exactly what a secured loan against any other asset does, and the fact that institutional products built this way exist says more about the market’s maturity than any price move. The other uses that hold up to scrutiny are less flashy. The transfer of value between parties without an intermediary that can reverse or block it, useful in contexts where that guarantee is worth more than speed. Holding it as a reserve asset on corporate balance sheets, which some companies already do and which has its own accounting implications. And the verifiability of the supply itself, which is the feature that gives rise to everything above. ## What it does not solve An honest educational article has to include this section. Volatility is real and is the reason a product like Circle’s requires overcollateralization and defines liquidation thresholds: whoever lends against bitcoin is assuming that the value of the collateral can move a great deal in a short time. The base layer is also not designed for the volume of everyday payments, a problem worked on in layers built on top. And it is worth noting that the product just described relies on a regulated custodian, which reintroduces an intermediary. That is not a contradiction: it is a different design for a different user, and it helps to know which one is being used. ## Where to start If you take a single thing from all this, let it be this: before forming an opinion about the price, look at the issuance schedule. It is published, it has not changed in more than fifteen years and it explains more than any headline. It is fifteen minutes of reading and it leaves you in a much better position to evaluate any product built on top, including the ones that will keep appearing this year. None of the above is investment advice or an opinion about the price of any asset. It is a description of how a technology works and of the products that already exist on it. ## Sources - USDC lending with bitcoin as collateral, cirBTC, Circle National Trust custody, Morpho and the New York exclusion: [Cointelegraph, “Circle enables Bitcoin-backed USDC borrowing for institutional clients,” September 21, 2026](https://cointelegraph.com/news/circle-launches-bitcoin-backed-usdc-borrowing-for-institutional-clients). - Block height (about 968,300 as of September 24, 2026), verifiable at any time: [blockchain.com/explorer](https://www.blockchain.com/explorer). - The 21-million cap, block reward and halving every 210,000 blocks: protocol consensus rules, public and verifiable in the reference implementation (Bitcoin Core) or any explorer. - Issuance table, current supply and annual rate: own calculation from the block height and the current reward. It is reproduced by multiplying blocks by reward in each period. See the rate and the fee before confirming every transaction. 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