# Why do bitcoins have a total limit?

There are a total of ~16 million bitcoins in existence, and 21 million total will be available. Therefore, there are ~5 million bitcoins still to be mined from now until around 2140. How much bitcoin is left to mine? - ...

Source: https://www.quora.com

Why does nobody can mine any bitcoin after 2140? Given this information is true?

It's not that you can't mine, just that no bitcoins are going to be created from mining. If miners stopped mining (which they will most probably do if they stop making money from it), it would mean the death of the blockchain. No mining means no transaction.

Currently, miners make money from two sources:

• Bitcoins created for each mined block
• Transaction fees paid for each transaction, that the miner is free to assign to wallet (guess who they will choose)

Transaction fees are just the fact that, if you pay me bitcoins, you'll have to pay a little more that is assigned to nobody. Miners will grab the pending transaction that they want to include in their mined blocks (those that pay the best, look at Fee statistics) given that a block can contain a limited amount of data, and keep the money for them.

To conclude, in 2140, if the network goes well, transaction fees should be enough for miners to earn their gigawatts. If not, then we will worry

The number of newly-created bitcoins with every mined block gets halved every 4 years on average. (More precisely, every 210,000 blocks). When bitcoin started, this was 50 new coins per block and currently it's down to 12.5 coins. This halvening creates a geometric progression which converges to the theoretical maximum number of bitcoins that can ever be mined, which happens to be 21 million.

Mathematically:

50 + 25 + 12.5 + 6.25 + ... = 100

100 × 210,000 = 21,000,000