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6.4Lesson 4 of 8
When the last bitcoin is mined
This lesson answers
- What happens when all 21 million bitcoin are mined?
- When will the last bitcoin be mined?
- How will miners get paid when there are no new bitcoin?
- Will there ever be exactly 21 million bitcoin?
New bitcoin will keep being created, in ever smaller amounts, until around the year 2140. After that, no new coins appear, but blocks keep coming every ten minutes or so. Miners will be paid only by the fees in the payments they include.
- New bitcoin per block
- …
- Fees in the newest block
- …
- Still to be created
- …
- Created so far
- …of 21 million
For now almost all of a miner's pay is new bitcoin. That share halves every four years or so.
See it on satoshis.watch →Why it ends just under 21 million
Each halving cuts the new bitcoin per block in half and rounds down to a whole satoshi. The amount shrinks to a single satoshi per block and then to zero. Add it all up and the total is 20,999,999.9769 bitcoin, a little under 21 million. The last satoshi of new money is due in block 6,929,999, at about ten minutes a block around the year 2140.
Fewer will ever be usable. The first block's 50 bitcoin can't be spent, and many coins are lost; see lost and sleeping coins.
What pays miners then
Today, fees are a small part of what a miner earns, as the figures above show. After the new coins stop, fees will be everything. Anyone sending a payment will still have to pay a miner to include it, and miners will compete for those fees the way they compete for blocks now.
The open question
What miners earn decides how much computing power protects the network. Some people worry that fees alone may not pay for enough mining, especially if most payments move to Lightning and only settle on the chain now and then. Others answer that the change is slow, over more than a hundred years, that fees rise when blocks are full, and that the rules can be adjusted by agreement if a real problem appears. Nobody can settle this yet; it is one of Bitcoin's long-term debates.
Check yourself
Practice, not a test. Think of your answer first, then reveal it.
1Why will the total never quite reach 21 million?Reveal
Each block's new bitcoin is halved and rounded down to whole satoshis, so the last fractions are lost and the total ends at about 20,999,999.98.
2What will miners earn after the last new bitcoin?Reveal
Only the fees of the payments they put in blocks.
3Does the last new bitcoin in about 2140 mean Bitcoin stops?Reveal
No. Blocks keep coming every ten minutes or so; only the creation of new coins stops.
Sources
- Bitcoin Core, GetBlockSubsidy: halving every 210,000 blocks, rounded down to whole satoshis.
- Totals and the last block with new bitcoin: worked out from that rule.
- Fees in the newest block: read from a Bitcoin node.