Bitcoin halving countdown

What is a Bitcoin halving?

Every 210,000 blocks — roughly every four years — the Bitcoin protocol cuts the block subsidy paid to miners exactly in half. The subsidy is the freshly-issued BTC each new block delivers to the miner that produced it; halvings are the mechanism by which Bitcoin's monetary policy enforces its 21-million-coin supply cap. The cut is automatic, hard-coded in the protocol, and impossible to skip or alter without a network-wide consensus change.

Why halvings matter

• Supply shock. The flow of new BTC entering the market suddenly halves. If demand stays constant, basic supply / demand logic says price rises.
• Schelling point. Markets coordinate around halvings as a known, calendared event — narrative and attention compound the supply-side effect.
• Miner economics. Less BTC per block forces unprofitable miners off the network, tightening the surviving fleet and resetting hashrate competition.
• Diminishing impact. Each halving cuts a smaller share of the total supply. The 2012 halving removed ~25% of cumulative issuance; the 2024 halving removed less than 2%. Future halvings will move the needle less than past ones.

How the ETA is calculated

The naive estimate is blocks_remaining × 10 minutes, because Bitcoin's difficulty adjustment targets a 10-minute average between blocks. In practice, real block times drift faster than 10 minutes most of the time (currently around 9.5–9.8 minutes on average), which means halvings consistently arrive a few weeks earlier than the naive estimate.

This tool reads the timestamps of the last 15 confirmed blocks from mempool.space and uses their rolling average as the per-block ETA basis. The result moves slightly as hashrate fluctuates — block time speeds up when miners come online, slows down when hashrate drops or during a difficulty epoch with a sudden upward retarget.

When does it all end?

The subsidy halves until it rounds to zero. That happens around the year 2140, at approximately block 6,930,000. After that, miners earn only from transaction fees. By the time of that final halving, more than 99.99% of all BTC that will ever exist will already have been mined — the 21-million cap is approached asymptotically, not exactly.