Approximately 18.59 million bitcoins were mined, or 89% of the maximum number of supply. There will never be more than 21 million BTC in circulation, unless there is a radical change in the supply mechanism of bitcoin.
Overall, one-fifth of Bitcoin hasn’t been moved for five years. Here’s why:
Satoshi’s cache. The mysterious creator of Bitcoin, Satoshi Nakamoto, may have mined around 1.1 million BTC in the first few months of its existence. Since then, Satoshi has not touched his stash, indicating that he cannot or will not put these coins into circulation. Because of this, the general consensus is that Satoshi’s bitcoin holdings have gone out of circulation, reducing the available supply by about 5.9%.
Lost private keys. One of the main ways to take bitcoins out of circulation is to simply lose them. Anyone who loses access to bitcoin will also lose the ability to spend their funds – about 20% of all bitcoins. Crypto data firm Glassnode estimates that around 3 million bitcoins will be lost forever.
Intentionally burned bitcoin. Most of the bitcoins were also sent to one of the various “burn addresses”. They are essentially vanity bitcoin addresses without a known private key, meaning that any bitcoin sent to that address is likely to be gone forever. So far, more than 2,700 BTC have been sent to over 100 addresses suspected of being burned, resulting in about $30 million worth of bitcoins being withdrawn from circulation.