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Episode 1: why there will only ever be 21 million bitcoin

The written guide to our first YouTube episode. Six short steps take you from how ordinary money grows to why the Bitcoin limit holds, with links to check every number yourself.

Watch: Only 21 Million Bitcoin, Ever. Here's Why. (8 minutes 41 seconds, YouTube)

Chapters

1. 0:00 Intro
2. 0:13 Money that can be printed
3. 1:41 The 21 million cap
4. 3:08 How new coins are made
5. 3:58 The halving
6. 5:54 Could someone change it?
7. 7:51 Recap

The lesson, step by step

Step 1: See how ordinary money grows

New pounds are created all the time, mostly by banks when they lend. The Bank of England can also create money electronically by buying government bonds, which is called quantitative easing. Over time prices rise. The UK Consumer Prices Index stood at 99.3 in January 2015 and 144.1 in September 2026, so £1 from 2015 buys about 69p of the same shopping today. You can try any year on The Melt.

Step 2: Meet the rule that never changes

Bitcoin is digital money with no boss. It runs on computers around the world that all follow the same rules. One rule caps the supply at just under 21 million bitcoin: 20,999,999.9769, because the maths rounds down over time. Each bitcoin splits into 100 million sats, so you never need a whole one. More in Sats explained.

Step 3: Learn where new coins come from

Payments are grouped into blocks, and a new block is added roughly every ten minutes. Miners compete to add each block by guessing numbers until one fits the rules. That costs real electricity, which makes cheating expensive. The winner is paid in brand new bitcoin, called the block reward. This is the only way new coins are created. See How mining works.

Step 4: Follow the halving

Every 210,000 blocks, about every four years, the block reward is cut in half. It started at 50 in 2009, then fell to 25 (November 2012), 12.5 (July 2016), 6.25 (May 2020) and 3.125 (April 2024). The next halving, to 1.5625, is expected around 2028. About 20.1 million bitcoin had been issued by late October 2026, and the last tiny fraction should be mined around 2140. Watch it on the halving countdown.

Step 5: See who enforces the limit

Thousands of people run Bitcoin software called nodes. Each node checks every block, including how many new coins it is allowed to create. A block that pays a miner too much is simply rejected. Raising the cap would need people to switch to new software, and anyone who does not keeps the old rules. That is why most people treat the limit as permanent. Read our node guide if you want to run one.

Step 6: Keep the limits of the idea in mind

A fixed supply does not guarantee a price. Demand still moves it, and it can fall a long way, sometimes fast. After 2140 miners will be paid only from fees, which already exist today. See After the last bitcoin.

Check it yourself

1. Open mempool.space and look at the latest block. Its reward should be 3.125 bitcoin plus fees.
2. Look up the live supply on How many Bitcoin are there?
3. Read the rule in plain words in the Bitcoin whitepaper, section 6.

Key takeaways

• There will never be more than about 21 million bitcoin.
• New coins are earned by miners, not printed, and the reward halves about every four years.
• Thousands of independent nodes reject any block that breaks the rule.
• You can check every one of these numbers yourself, for free.
• A fixed supply does not stop the price from falling.

Lesson: Why 21 million? Lesson: The halving Next: Episode 2

FAQ

Not financial advice. General education only. Bitcoin prices can swing hard. Never put in more than you can afford to lose, and do your own research. We will never ask for your recovery words or keys.