Key highlights:

According to estimates from experts, the last Bitcoin will be mined in the year 2140

The supply of new BTC entering circulation gradually decreases over time

Every four years, the Bitcoin halving reduces the amount of BTC miners earn in half

Bitcoin supply dynamics & halving

At the moment, there exist about 17.3 million BTC, meaning that there are approximately 3.7 million BTC left to be mined before the maximum supply of 21 million BTC is reached. The actual supply of Bitcoin in circulation is likely substantially lower than 17.3 million – cryptocurrency security expert Jameson Lopp estimates that 4 million BTC are permanently lost, either because their owners have lost their private keys or died.

Bitcoin miners are incentivized to provide their hashpower to the network with BTC that is created to reward whoever places the next block on the Bitcoin blockchain. Right now, the block reward is 12.5 BTC, and this amount is set to drop to 6.25 BTC with the next halving, which is expected to occur in May 2020.

Buy/Sell Bitcoin (BTC)

The Bitcoin halving is eagerly anticipated by those who speculate on the price of Bitcoin, as it lowers the supply of fresh BTC entering the market – the increased scarcity is a beneficial factor on the value of BTC. Miners have to sell a portion of the mined BTC to cover operating costs (electricity, hardware, employees...).

The halving of block rewards occurs every 210,000 blocks, and the time of future halvings can be calculated as a new block is added to the Bitcoin blockchain at an average rate of one every 10 minutes.

The next Bitcoin halving is expected in May 2020

The next Bitcoin halving, which is expected to happen in May of 2020, will be the third Bitcoin halving. Here's the halvings that have happened so far and the associated block reward reductions. In total, there will be 32 Bitcoin halvings before the last BTC is mined.

First Bitcoin halving: November 28, 2012 (from 50 BTC to 25 BTC)

November 28, 2012 (from 50 BTC to 25 BTC) Second Bitcoin halving: July 6, 2016 (from 25 BTC to 12.5 BTC)

July 6, 2016 (from 25 BTC to 12.5 BTC) Third Bitcoin halving: estimated to happen on May 14, 2020 (12.5 BTC to 6.25 BTC)

estimated to happen on May 14, 2020 (12.5 BTC to 6.25 BTC) Fourth Bitcoin halving: estimated to happen in 2024 (6.25 BTC to 3.125 BTC)

In general, halvings are seen as positive events for Bitcoin's price.

It's going to take a while to mine all Bitcoins

The last Bitcoin is estimated to be mined in 2140, when the block reward would drop below 1 satoshi (the smallest denomination of BTC). Of course, this would require Bitcoin miners to be around 122 years from now, which is far from a certainty. At that point, miners would be incentivized to maintain the network because they would still collect fees for securing transactions even though there would be no more block rewards.

If you’re curious, you can check out this interesting table which contains estimates on when future Bitcoin block reward halvings are expected to occur.

What will happen when the last Bitcoin is mined?

Unless a protocol change is enacted that will raise the maximum amount of Bitcoins that can exist (a very unlikely scenario), the supply of new BTC will eventually run out permanently. When that happens, miners will only be compensated with transaction fees and stop receiving block rewards. So, we should hope that Bitcoin is heavily adopted and commonly used by 2140, otherwise we could see miners abandoning ship!

When there's no Bitcoin left to mine, there's also the chance that transaction fees would increase sharply to account for the fact that there's no more block rewards. However, a lot of things could change between now and 2140 and there's no guarantee that the Bitcoin network will survive for more than a century.