What is the total supply of Bitcoin?

The total supply of Bitcoin is capped at 21 million coins. This limit was set by the original design of the Bitcoin protocol, specified in the whitepaper authored by Satoshi Nakamoto. The issuance of new bitcoins is programmed to follow a predetermined schedule, with new bitcoins created as block rewards for miners who successfully validate and add new blocks to the blockchain through the process of mining. However, the rate of new bitcoin issuance decreases over time through a process known as "halving."

Approximately every four years, or after every 210,000 blocks are mined, the block reward for miners is halved. This reduction in block rewards ensures that the total supply of Bitcoin approaches its maximum limit of 21 million coins gradually over time. As of the most recent halving event in May 2020, the block reward was reduced from 12.5 bitcoins per block to 6.25 bitcoins per block. This halving process will continue approximately every four years until the maximum supply of 21 million bitcoins is reached, which is estimated to occur around the year 2140.

The capped supply of 21 million bitcoins is one of the key features of Bitcoin that distinguishes it from traditional fiat currencies, which are subject to inflationary pressures and centralized control by governments and central banks. The scarcity of Bitcoin is often cited as a factor contributing to its value proposition and investment appeal, as it offers a deflationary monetary policy and a hedge against inflationary risks.