As of the end of 2024, Bitcoin had undergone 4 halvings.
The first occurred in 2012, reducing the mining reward from 50 BTC to 25 BTC. The second followed in 2016, cutting it to 12.5 BTC, and the third arrived in 2020, lowering the reward to 6.25 BTC.
Bitcoin’s fourth halving occurred in April 2024 at block 840,000. It reduced the block subsidy to 3.125 BTC. These events happen after every 210,000 blocks, which works out to approximately once every four years, although the exact dates vary with mining speed.
A common mix-up is counting Bitcoin’s launch in 2009 as a halving. The original 50 BTC reward was the starting subsidy, not a halving event. Future halvings are programmed to continue until new-coin issuance eventually becomes negligible.