Bitcoin's protocol mandates a maximum supply of 21 million coins to prevent inflation. However, the actual circulating supply is significantly lower due to permanently lost coins.
Estimates from firms like Chainalysis suggest roughly 3.7 million Bitcoin may be unrecoverable. Other estimates place the figure between 4 and 5 million, representing nearly 18% to 24% of the total cap.
Losses stem primarily from lost private keys, forgotten wallet passwords, discarded hardware, and deaths without inheritance plans. Self-custody losses (1.6 million BTC) have exceeded exchange-related losses (1.2 million BTC) since Bitcoin's inception.
Satoshi Nakamoto, Bitcoin's creator, is believed to hold approximately 1 million coins in inactive wallets. Whether these are lost or deliberately untouched remains unknown, but they are effectively removed from circulation.
Real-world cases highlight the finality of such losses. Stefan Thomas has only two password attempts left to unlock a wallet containing 7,002 BTC. James Howells accidentally threw away a hard drive holding 8,000 BTC, now buried in a landfill.
Burning Bitcoin, sending it to an address with no known private key, also contributes to reduced supply. One common burn address has received thousands of BTC permanently.
This lost supply reinforces Bitcoin's 'digital gold' narrative, as effective scarcity exceeds the protocol's theoretical cap. The remaining coins become more valuable per unit if demand remains constant or grows. While the rate of loss is expected to slow as security improves, the gap between theoretical and actual supply will persist.