🔒 Absolute Scarcity: 21 Million
Not "for now." Not "until a committee decides." Ever.
Start the interactive lesson →
21 million. Full stop.
There will only ever be 21 million bitcoin.
Not "for now." Not "until a committee decides otherwise."
Ever.
The hard cap
The 21 million limit is written into Bitcoin's code. No government, company, or individual can create more.
Changing it would require nearly the entire network to agree to break the one rule that makes Bitcoin valuable in the first place.
Turkeys don't vote for Christmas.
The halving
New bitcoin enters circulation as a reward to miners (more on them in Pillar 3).
Roughly every 4 years, that reward cuts in half — a "halving."
Issuance keeps shrinking until the last bitcoin is mined around the year 2140.
Two very different curves
Fiat currencies can be issued indefinitely, whenever a central bank decides to.
Bitcoin's issuance is scheduled, shrinking, and public — anyone can calculate exactly how much will exist at any future date.
One is a policy decision. The other is arithmetic.
Try it: Two supply curves
Drag the year toward 2140 and watch what each curve does.
Bitcoin's issuance is scheduled, shrinking, and public — it flattens into a hard 21 million ceiling. A fiat money supply compounds indefinitely. Drag the year and compare them directly. Open the Two Supply Curves tool →
Quick check: How often does the mining reward get cut in half?
- Every year
- Roughly every 4 years ✓
- Whenever the network votes on it
Every 210,000 blocks — which at about ten minutes per block works out to roughly four years. It's a schedule, not a decision.
Quick check: What happens to Bitcoin's issuance rate over time?
- It shrinks on a fixed, predictable schedule until it hits zero ✓
- It rises to keep up with demand
- It stays constant forever
Each halving cuts new supply in half. The curve flattens toward 21 million and then stops permanently around 2140.
Next up
Fixed supply is only half the story.
Who enforces these rules if there's no CEO?