<p>The whitepaper doesn't mention any specific supply cap, and actually the distribution parameters it suggests are very different from the actual parameters implemented in Bitcoin:</p>
<blockquote>
<h3>6. Incentive</h3>
<p>By convention, the first transaction in a block is a special transaction that starts a new coin owned by the creator of the
block. This adds an incentive for nodes to support the network, and
provides a way to initially distribute coins into circulation, since
there is no central authority to issue them. The steady addition of a
constant of amount of new coins is analogous to gold miners expending
resources to add gold to circulation. [...] Once a
predetermined number of coins have entered circulation, the incentive
can transition entirely to transaction fees and be completely
inflation free.</p>
</blockquote>
<p>I would interpret the words &quot;steady addition of a constant of amount of new coins&quot; as a constant mining subsidy that abruptly ends after a predetermined amount has been mined.</p>
<p>The announcement of the release of the first Bitcoin client by Nakamoto mentions the supply cap and parameters as we know them today:<br />
<a href="https://www.metzdowd.com/pipermail/cryptography/2009-January/014994.html" rel="nofollow noreferrer">https://www.metzdowd.com/pipermail/cryptography/2009-January/014994.html</a></p>
<blockquote>
<p>Total circulation will be 21,000,000 coins.  It'll be distributed to
network nodes when they make blocks, with the amount cut in half every
4 years.</p>
<p>first 4 years: 10,500,000 coins<br />
next 4 years: 5,250,000 coins<br />
next 4 years: 2,625,000 coins<br />
next 4 years: 1,312,500 coins etc...</p>
</blockquote>
<p>And of course, you can look into the source code of Bitcoin Core or any other Bitcoin node software to verify the supply cap for yourself. See <a href="https://bitcoin.stackexchange.com/a/110161/121614">this answer</a>.</p>

CC BY-SA 4.0
2022-06-02T09:32:19.970Z
2022-06-02T09:32:19.970Z
Vojtěch Strnad
<p>Everyone says that the Bitcoin supply is capped at 21 million. But how did everybody come to this number? In Nakamoto's paper, I could not find this number. Can someone explain where it is or how we can infer this maximum based on Nakamoto's paper? I'm not a mathematician. Maybe, it's clear for everybody but to me this seems to be a fantasy number.</p>
<pre><code>Nakamoto, S. (2008). Bitcoin: A peer-to-peer electronic cash system. Decentralized
Business Review, page 21260.
</code></pre>
<p>Thanks in advance for your reply.</p>

CC BY-SA 4.0
2022-06-02T20:20:57.140Z
Does this answer your question? [How is the bitcoin 21 million cap implemented?](https://bitcoin.stackexchange.com/questions/2756/how-is-the-bitcoin-21-million-cap-implemented)
chytrik
<cryptography><money-supply><satoshi-nakamoto><shrinking-money-supply><supply>
How do we know that Bitcoin supply is actually capped at 21 million?
TFT
# How do we know that Bitcoin supply is actually capped at 21 million?

(Asked by: username_0 on 2022-06-02)

Everyone says that the Bitcoin supply is capped at 21 million. But how did everybody come to this number? In Nakamoto's paper, I could not find this number. Can someone explain where it is or how we can infer this maximum based on Nakamoto's paper? I'm not a mathematician. Maybe, it's clear for everybody but to me this seems to be a fantasy number.

```
Nakamoto, S. (2008). Bitcoin: A peer-to-peer electronic cash system. Decentralized
Business Review, page 21260.

```

Thanks in advance for your reply.

**Tags:** cryptography, money-supply, satoshi-nakamoto, shrinking-money-supply, supply

> **Comments:**
> **username_1**: Does this answer your question? [How is the bitcoin 21 million cap implemented?](https://bitcoin.stackexchange.com/questions/2756/how-is-the-bitcoin-21-million-cap-implemented)  

---

## 1 answers

### Answer by username_2 on 2022-06-02. Score: 2 | Accepted answer

The whitepaper doesn't mention any specific supply cap, and actually the distribution parameters it suggests are very different from the actual parameters implemented in Bitcoin:

> ### 6. Incentive
>
> By convention, the first transaction in a block is a special transaction that starts a new coin owned by the creator of the
> block. This adds an incentive for nodes to support the network, and
> provides a way to initially distribute coins into circulation, since
> there is no central authority to issue them. The steady addition of a
> constant of amount of new coins is analogous to gold miners expending
> resources to add gold to circulation. [...] Once a
> predetermined number of coins have entered circulation, the incentive
> can transition entirely to transaction fees and be completely
> inflation free.

I would interpret the words "steady addition of a constant of amount of new coins" as a constant mining subsidy that abruptly ends after a predetermined amount has been mined.

The announcement of the release of the first Bitcoin client by Nakamoto mentions the supply cap and parameters as we know them today:  
<https://www.metzdowd.com/pipermail/cryptography/2009-January/014994.html>

> Total circulation will be 21,000,000 coins. It'll be distributed to
> network nodes when they make blocks, with the amount cut in half every
> 4 years.
>
> first 4 years: 10,500,000 coins  
> next 4 years: 5,250,000 coins  
> next 4 years: 2,625,000 coins  
> next 4 years: 1,312,500 coins etc...

And of course, you can look into the source code of Bitcoin Core or any other Bitcoin node software to verify the supply cap for yourself. See [this answer](https://bitcoin.stackexchange.com/a/110161/121614).


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