BEGINNER PATH / 08

WHY ONLY 21 MILLION?

Bitcoin's monetary rules create new bitcoin according to a predictable schedule. The block subsidy is reduced every 210,000 blocks and issuance eventually falls to zero, leaving a maximum supply approaching 21 million bitcoin.

200950 BTC

Bitcoin began with a 50 BTC block subsidy.

210,000 BLOCKSHALVING

Roughly every four years, the subsidy is cut in half.

20243.125 BTC

The fourth halving reduced the subsidy to 3.125 BTC per block.

OVER TIMELESS NEW BTC

Each halving makes new issuance smaller and more gradual.

~2140SUBSIDY → ZERO

Current rules project the final issuance around the year 2140.

WHO ENFORCES IT? / 09

THE LIMIT IS A NETWORK RULE.

Miners cannot simply award themselves any amount they choose. Nodes validate blocks and reject blocks that create more reward than the consensus rules permit.
MINERS

PROPOSE BLOCKS

Miners perform proof-of-work and may include a coinbase transaction claiming the permitted subsidy plus transaction fees.

NODES

CHECK THE RULES

Full nodes independently validate blocks. A block that violates the reward rules is not accepted as valid by nodes following the existing consensus rules.

AFTER SUBSIDY

FEES REMAIN

Mining does not end when new issuance ends. Transaction fees are designed to remain part of the incentive for including transactions in blocks.

UNDERSTAND FEES →
21 million does not mean 21 million people can each own one bitcoin. Bitcoin is divisible into satoshis, so ownership can be distributed in much smaller fractions.