Bitcoin Halving Dates

Bitcoin’s subsidy schedule is enforced by a single consensus function: nSubsidy = 50 BTC; nSubsidy >>= floor(height / 210000); return nSubsidy. Every 210,000 blocks the right-shift effectively halves the reward; after 33 such halvings the reward in satoshis rounds to zero and the schedule terminates. BIP-0042 formalised this behaviour in 2014 and added a guard against over-shifting the reward past the 64-halving boundary. The cap was already enforced in code; the BIP made it spec.

The four-year cadence is shorthand for ten-minute blocks × 210,000. The protocol re-targets difficulty every 2,016 blocks to hold the average interval near ten minutes, but the realised average has been closer to nine and a half. That undershoot is why every halving so far has arrived ahead of its four-year-from-prior date.

The +12-month column moves in one direction top to bottom. Each forward return has been a fraction of the one before. The 2012–2013 run printed a multi-thousand-percent gain on a tiny base. The 2016–2017 cycle came in at a few hundred percent, the 2020–2021 cycle in the mid hundreds, the 2024 cycle in the low thirties. Whether the cause is maturation (a larger asset can’t move as fast), saturation (institutional flow now absorbs the marginal halving), or both, the column trends one way.

The supply-after column tells the other half. By the start of epoch 5, more than 96% of the eventual asymptote will already be in circulation; epochs 6 onward add only the long tail. New supply is front-loaded and its marginal effect on the float is shrinking, regardless of the causal story.

The protocol pays out by block height, not by calendar. Every projected halving in the table assumes a flat four calendar years from the prior halving — a planning convention, not a forecast. Real block intervals have averaged 9.5–9.7 minutes against the ten-minute target, which is why halvings 1, 3, and 4 each landed earlier than the strict four-year date implied. The bias is one-sided. When miners pile in faster than the next difficulty re-target, blocks land closer together, and halvings arrive sooner. A live block-anchored estimate sits on Halving Countdown.

Halving-day prices are daily closes, not block-time prices. The block that triggers the halving is mined at a specific minute; the price snapshot published here is the daily close on that calendar day. For halving 4, the block was mined nine minutes after midnight UTC on 20 April 2024, but the pipeline records the halving against 19 April. Either anchor is defensible and both are widely cited; the calendar day keeps the +12-month column apples-to-apples.

Forward returns sit on a single day. The +12-month return is close-to-close on a fixed calendar offset, not the cycle peak. Each cycle has historically peaked 12–18 months after the halving, not exactly 12. The headline column understates the cycle peak and overstates the return on cherry-picked dates immediately around the trough.

Cycle 4 isn’t over. The 2024 row in the table is closed arithmetic only on the +12-month price. Whether the broader cycle behaves like the prior three is, as of this writing, an open question. The honest framing is forward 12 months, not cycle return.

Frequent searches on “bitcoin halving dates”, answered against the schedule.