Bitcoin's fourth halving took effect at block 840,000, cutting the block subsidy paid to miners from 6.25 BTC to 3.125 BTC. The event, written into the protocol from the start, arrives roughly every four years and halves the rate at which new coins are issued.

What changed at block 840,000

Miners are paid in two ways: the block subsidy of newly issued coins, and the transaction fees included in the block. The halving affects only the first. Overnight, the newly issued portion of each block's reward fell by half, while the number of blocks per day and the ten-minute target were untouched.

For an operation running the same machines at the same electricity cost, revenue from the subsidy dropped by 50 percent the moment the halving activated.

The pressure on margins

A halving is the sharpest scheduled test of a miner's cost structure. Operators whose electricity and hardware costs sat comfortably below their revenue before the event can suddenly find themselves close to break-even.

The usual responses are familiar from previous cycles:

  • Retiring older, less efficient machines that no longer cover their power cost.
  • Relocating to cheaper energy or renegotiating power contracts.
  • Leaning more heavily on transaction fees, which become a larger share of the total reward as the subsidy shrinks.

Less efficient hardware tends to switch off in the weeks after a halving, which eventually feeds through to a downward difficulty adjustment and gives the survivors some relief.

Fees matter more each cycle

With every halving the subsidy falls and transaction fees make up a growing part of miner income. That trajectory is by design: the protocol will issue its last new coins in the next century, after which fees are meant to fund network security entirely. Each halving is a step along that path.

The longer arc

Three previous halvings, in 2012, 2016 and 2020, followed the same script: an immediate revenue shock, a shakeout of the least efficient capacity, and a gradual rebalancing. The 2024 event fits the pattern. For miners the message is unchanged from the day the network launched: efficiency is not a luxury, it is the thing that decides who is still running after the reward is cut.